Birth of a Nation Media Effects: Ang (2023)

What this is. The paper’s core results, the identification design, and the estimating equations: enough to understand what was found and how, without reading all 37 pages. To replicate or extend, read the original at doi.org/10.1257/aer.20201867.

TL;DR

Ang (2023) provides causal evidence on the social imprint of D. W. Griffith’s 1915 film The Birth of a Nation, a fictional depiction of the founding of the Ku Klux Klan that reached an estimated 10 million Americans during a five-year road show. Exploiting the film’s staggered county-level distribution, the paper estimates roughly fourfold increases in lynchings and race riots around arrival; conventional tests are imprecise (p = 0.06 and p = 0.30), while randomization-inference tests support the increases. For longer-run effects, theater presence in 1914 instruments for whether a county received the film; the 2SLS estimate shows a 66 percentage-point increase in the probability of a second-KKK klavern forming by 1930 (Fryer and Levitt (2012) provide Klan history and membership benchmarks). Road-show counties remain significantly more likely to contain hate groups and to experience higher hate crime rates a century later, with effects extending beyond anti-Black incidents to other racial, religious, and sexual minorities. Mediation analysis following Dippel, Ferrara, and Heblich (2020) indicates the long-run effects run almost entirely through the historical formation of second-KKK chapters. Esposito et al. (2023) is a companion paper on the film’s rhetorical legacy that independently validates the screening data.

Core results

Magnitudes as reported. Randomization-inference p-values cited for R1 and R2 (the rarity of events makes conventional standard errors imprecise). Locators point into the source PDF.

#	Result	Locator	Magnitude as reported
R1	Lynching probability rose around the month of the film’s county arrival	Figure 3 Panel A, p. 1438; text p. 1437	beta_0 = 0.0011 (mean = 0.0003); ~4x monthly base rate; conventional p = 0.06; randomization-inference p < 0.01
R2	Race riot probability rose in the three months following the film’s arrival	Figure 3 Panel B, p. 1438; text p. 1437	beta_0 = 0.00034 (mean = 0.00009); ~4x base rate; conventional p = 0.30; randomization-inference p < 0.05
R3	Theater presence in 1914 strongly predicts screening (first stage)	Table 3 col. 1, p. 1444	Coefficient = 0.324 (se = 0.024); mean screened = 0.20; Kleibergen-Paap F = 185.34
R4	Screening raised klavern probability by 66 pp (2SLS main estimate)	Table 4 Panel C col. 1, p. 1446; OLS: Panel A col. 1	2SLS = 0.662 (se = 0.138); mean = 0.313; p < 0.001; OLS = 0.111 (se = 0.021)
R5	Screening raised klavern intensity (klaverns per 10,000 US-born White males)	Online Appendix Table A.II; p. 1449	beta_IV = 0.95 (p = 0.036); implies ~1 million additional Klansmen induced
R6	Road-show counties ~90% more likely to host a hate group in 2000-2019	Table 5 col. 2, p. 1454	2SLS = 0.366 (se = 0.100); mean = 0.374; treatment mean 0.60 vs control mean 0.32
R7	Hate crime rate ~85% higher in road-show counties, 2000-2018; elevated for anti-Black and anti-other-minority crimes	Table 6 cols. 1-4, p. 1455	2SLS = 1.177/100k (se = 0.494; mean = 1.376); anti-Black = 0.516 (p = 0.003); anti-other minorities = 0.561 (p = 0.030); anti-White = 0.101 (insignificant)
R8	Fully controlled theater instrument strongly predicts film screening	Table 3 col. 5, p. 1444	Coefficient = 0.219 (se = 0.023); Kleibergen-Paap F = 87.45; N = 3,103
R9	Theater presence is unrelated to observed historical racism and demographic measures	Figure 4, p. 1441; Online Appendix Figure A.XIV cited p. 1442	Conditional coefficients are precise zeros, with magnitudes below 0.05 standard deviations; no relation to pre/post-film population measures
R10	Theater presence does not predict klavern formation in Kansas, where the film was banned	Table 2 Panel A col. 1, p. 1442	Reduced form = -0.138 (se = 0.111); outside Kansas = 0.146 (se = 0.026)
R11	Theaters opened before 1918 predict later klavern formation; post-1918 theaters do not	Figure 5, p. 1443	Theater-opening estimates are significant and positive before 1918; estimates after 1918 are insignificant
R12	Historical klavern effect persists across five restricted samples	Table 4 Panel C cols. 2-6, p. 1446	2SLS = 0.478 (se = 0.101), 0.532 (0.110), 0.535 (0.138), 0.595 (0.157), 0.531 (0.109); all p < 0.001
R13	Klan formation effect is largest where religious participation was low	Figure 6, pp. 1448-1449	IV effect = 1.01 below-median versus 0.39 above-median religious membership; p(diff) < 0.01
R14	Historical screenings predict third-KKK presence in the 1960s	Table 5 col. 1, p. 1454	2SLS = 0.132 (se = 0.062); mean = 0.106
R15	Long-run hate-group effects are concentrated in KKK and other White supremacist groups	Table 5 cols. 3-5, p. 1454	2SLS: KKK = 0.133 (se = 0.071), White supremacist = 0.314 (se = 0.085), other groups = 0.010 (se = 0.044; insignificant)
R16	State-level estimates suggest higher Klan membership intensity	Online Appendix Figure A.XIX; discussed p. 1449	IV coefficient = 0.13 (p = 0.107); implied persuasion rate = 18%, roughly one member per six US White male moviegoers
R17	Permutation tests show the short-run violence estimates are unusual under placebo dates	Online Appendix Figure A.XII; discussed p. 1439	Lynching placebo estimates exceed the actual in 2/500 month-0 and 6/3,000 post-treatment tests; race-riot proportions are 7.4% and 4.8%
R18	The 1918 film Mickey does not produce an immediate violence spike	Online Appendix Figure A.XIII; discussed p. 1439	Little evidence of increased violence after Mickey screenings; no point estimates reported in the main text
R19	Film penetration predicts minority, but not White, homicide increases after release	Online Appendix Figure A.VI; discussed pp. 1438-1439	Significant increase in minority homicides over the following decade; no change in White homicides; numerical estimates are not printed in the main text
R20	Historical screenings do not change contemporaneous political outcomes	Online Appendix Figures A.XXII-A.XXIV; discussed p. 1453	Null effects on Democratic vote share and DW-NOMINATE scores; numerical estimates are not printed in the main text
R21	1946 survey responses indicate increased KKK knowledge and approval	Online Appendix Table A.X; discussed p. 1454	Greater KKK knowledge and reduced desire to ban the organization, particularly among White respondents
R22	1970s survey responses indicate more negative views of Black people and leaders	Online Appendix Figure A.XXV; discussed p. 1454	Less favorable views of Black people, civil-rights leaders, and Black militants; numeric estimates are not printed in the main text
R23	Census naming patterns are consistent with imitation of the film’s protagonist	Online Appendix Figure A.XXI; discussed p. 1453	Large increase in the share of White boys named Benjamin in road-show counties during the decade after release; no point estimate in the main text
R24	Mediation analysis suggests nearly all long-run effects run through historical KKK formation	Online Appendix Table A.XVII; discussed pp. 1456-1457	Under strong identifying assumptions, nearly all long-run effects are mediated by second-KKK formation; numerical direct and indirect effects are not printed in the main text
R25	Historical klavern effects appear across counties with different demographic and racial histories	Figure 6, pp. 1448-1449	Positive and similar IV estimates across population, density, Black-share, Democratic-support, illiteracy, Confederate status, and prior violence/monument splits
R26	Film distribution was associated more with market size and media access than measured preexisting racial animus	Table 1, p. 1436	Treatment versus control counties with theaters: population 75.63k vs 25.45k; newspaper circulation 0.18 vs 0.05; media markets 1.30 vs 0.81; maximum seats 786.94 vs 370.95

Overall (paper’s conclusion). Screenings of The Birth of a Nation triggered near-term racial violence and fueled the nationwide revival of the Ku Klux Klan. That historical catalysis persists a century later: road-show counties experience markedly higher rates of organized White supremacist activity and hate crimes directed at a wide range of minority groups. The paper’s mediation analysis suggests, under strong identifying assumptions, that these long-run effects run almost entirely through the Klan chapters the film historically seeded.

Theory / model

The paper proposes no formal economic model. The research design tests three related hypotheses.

Short-run violence hypothesis. Exposure to The Birth of a Nation increased racial hate in the county in the months of the screening, through some combination of: (i) persuasion and direct belief change about racial hierarchy, (ii) emotional responses that lowered inhibitions for violence, and (iii) public revelation of latent racism that reduced the perceived social cost of acting on racial animus. The conventional estimates are imprecise (p = 0.06 for lynchings and p = 0.30 for race riots); the paper reports stronger support from randomization inference.

Medium-run KKK formation hypothesis. Exposure catalyzed the formation of second-KKK chapters that would not have formed otherwise. Proposed channels include: (a) provision of common cultural symbols and imagery (white robes, cross burning, which the second KKK copied directly from the film’s fictionalized Klan, unlike the first Reconstruction-era Klan; Section I.C, p. 1432), (b) reduction of coordination costs among individuals seeking to organize around racial ideology, and (c) persuasion of latent adherents into active participants.

Long-run persistence hypothesis. The Klan chapters historically seeded by the film transmitted racial hate across generations through social institutions and networks, so areas with early klavern formation exhibit higher hate-group presence and hate crime rates decades after the second KKK’s formal dissolution.

Three mechanism channels are discussed (Section V, pp. 1452-1453):

1. Social norm erosion and coordination. Public screenings publicly revealed latent racism and unraveled norms that had suppressed discriminatory behavior, facilitating coordination among individuals predisposed to racial animus. This channel is consistent with Bursztyn, Egorov and Fiorin (2020) and with the heterogeneous-effects finding that the film’s catalyzing impact was largest in counties with below-median religious participation, where prior social coordination infrastructure was weakest.
2. Media imitation. The second KKK adopted the film’s specific iconography: white robes, hoods, and cross burning. None of these practices appeared in the Reconstruction-era Klan; all were drawn directly from the film. Full-count census data also show that White parents in road-show counties became more likely to name their sons “Benjamin,” after the film’s protagonist.
3. Persuasion and preference change. Survey evidence from the 1946 Gallup and 1970s ANES shows road-show counties were associated with less favorable attitudes toward African Americans and greater Klan approval, consistent with a shift in racial preferences among viewers.

Method

The paper applies two identification strategies, linked by the same instrument.

Event study (short-run racial violence). The film’s five-year road show created staggered county-level variation in when and whether each county received a screening. This variation, combined with the demonstrated role of market factors (population size, theater capacity, urban density) rather than racial animus in determining where the film was shown, supports a parallel-trends assumption for an event study comparing counties before and after the film’s arrival. The key estimate is the coefficient at $\tau = 0$ (month of arrival) from Equation 1.

Instrumental variables (long-run effects). Whether a county received the film is endogenous to local characteristics. The paper instruments for county-level screening using movie theater presence in 1914, the year before the film’s release. Theaters predict screenings because the film required elaborate projection equipment and large paying audiences, so distributors prioritized counties with existing cinema infrastructure. Exogeneity is validated by four pieces of evidence: (i) theater presence in 1914 is uncorrelated with pre-period racial violence, Democratic vote shares, and Black population shares, conditional on controls (Figure 4, p. 1441); (ii) in Kansas, where the film was banned statewide, theaters in 1914 do not predict klavern formation (Table 2 Panel A), supporting the exclusion restriction; (iii) theaters opened before 1918 predict future klavern formation, while those opened after 1918 do not (Figure 5, p. 1443); (iv) Oster’s delta ranges from 1.7 to 4.8 in matched samples (p. 1451), indicating that selection on unobservables would need to be several times larger than selection on observables to explain the estimates away. For long-run outcomes, the same IV design is re-estimated with hate groups (2000-2019) and hate crime rates (2000-2018) as dependent variables. DellaVigna and La Ferrara (2015) provide the media-economics benchmark establishing that selection into viewership of entertainment media is driven primarily by demand for entertainment rather than pre-existing racial preferences.

This design extends the approach of Yanagizawa-Drott (2014), who identifies the causal effect of Rwanda radio propaganda on genocide participation using a topography-based instrument for signal reception, to the case of popular fictional entertainment media in a democratic setting.

Empirical specifications

Event study (Equation 1, p. 1437). Weekly county panel data, 1913-1922, all US counties:

$$y_{c,t} = \delta_c + \lambda_{s,t} + \sum_{\tau=-6}^{6} \beta_\tau \, Show_\tau + \epsilon_{c,t} \tag{1}$$

Here $y_{c,t}$ is an indicator for whether a lynching (or race riot) occurred in county $c$ at week $t$; $\delta_c$ are county fixed effects; $\lambda_{s,t}$ are state-week fixed effects, absorbing state-wide shocks and differential secular trends; $Show_\tau$ are dummies for months relative to the film’s first screening in the county ($\tau = 0$ = month of arrival), defined as five-week intervals centered on the week of the film’s premiere in each county; $Show_6$ ($Show_{-6}$) equals 1 for periods six or more months after (before) a screening; the omitted category is the last month before arrival; standard errors clustered by state. Sample: 3,104 US counties (Washington DC dropped due to collinearity with state fixed effects). Outcome means: 0.0003 (lynchings) and 0.00009 (race riots) per county-week.

IV first stage (Equation 3, p. 1440):

$$\text{Screened}_c = \delta_s + \gamma \, \text{Theater}_c + X'_c \Lambda + v \tag{3}$$

where $\text{Screened}_c$ is a binary indicator for whether county $c$ received the film from 1915 to 1919; $\text{Theater}_c$ is a binary indicator for a movie theater in county $c$ in 1914; $\delta_s$ are state fixed effects; $X'_c$ is the vector of demographic, social-capital, media, and racism controls described in Table 3. The preferred fully-controlled specification (col. 5, Table 3) yields a coefficient of 0.219 (se = 0.023) and Kleibergen-Paap F = 87.45, well above the 16.38 maximal-10%-bias benchmark.

IV second stage (Equation 2, p. 1440):

$$KKK_c = \lambda_s + \beta \, \text{Screened}_c + X'_c \Gamma + u \tag{2}$$

where $KKK_c$ is the outcome of interest (klavern indicator by 1930, hate-group indicator, or hate crime rate); $\beta$ is the LATE identifying the average causal effect of screening on compliers; standard errors clustered by state throughout. The same specification is applied to hate-group presence (Table 5) and hate crime rates (Table 6) to produce the long-run estimates.

Controls (Table 3) include: a quadratic in total population, density, Black population and share, US-born share, and draft-eligible age share (1910 Census); urban share, illiteracy rate, voter turnout 1912, religious organization share (1906 Census of Religious Bodies), occupational income score, and quadratics in railroad distance to the two nearest major cities; per-capita newspaper circulation and number of media markets in 1912 (Gentzkow, Shapiro, and Sinkinson 2011); historical lynching count 1900-1905, Democratic vote share 1912, Confederate monuments by 1914, and NAACP chapter presence in 1914.

Robustness includes: propensity-score matching across three comparison groups; restriction and exclusion of neighboring counties; restriction to counties with at least one digitized local newspaper; alternative instruments (theaters per 1,000 White residents, maximum seating capacity, year of first theater, showings of Mickey or The Million Dollar Mystery); spatial-correlation-robust standard errors (Conley 1999; Muller and Watson 2021); and placebo tests using screenings of the 1918 comedy Mickey, which show no significant effect on racial violence or Klan formation.

Kansas exclusion-restriction test (Table 2, p. 1442; written out from the reduced-form specification). The paper regresses the 1930 klavern outcome on theater-stock measures, the full Table 3 controls, and state fixed effects, separately for Kansas and non-Kansas counties:

$$\text{Klavern}_{c,1930} = \lambda_s + \rho \, \text{TheaterStock}_{c,1914} + X'_c \Pi + e_c$$

The theater-presence coefficient is -0.138 (se = 0.111; N = 105) in Kansas and 0.146 (se = 0.026; N = 2,998) outside Kansas. Standard errors are clustered by state.

Theater-timing exclusion test (Figure 5, p. 1443; written out from the plotted specification). The outcome is klavern presence by 1930, with mutually exclusive indicators for the year the county’s first theater opened and an omitted group of counties without a theater by 1930:

$$\text{Klavern}_{c,1930} = \lambda_s + \sum_{y \neq \text{no theater by 1930}} \rho_y \, \mathbb{1}(\text{first theater year}_c = y) + X'_c \Pi + e_c$$

The regressions include Table 3 controls and state-clustered standard errors. The source reports significant positive estimates for theaters opened before 1918 and insignificant estimates after 1918; it does not tabulate individual coefficients.

Heterogeneity and long-run outcome specifications. Figure 6 estimates Equation 2 separately across county subgroups, omitting the split variable from controls; standard errors are clustered by state. Tables 5 and 6 reuse the Equation 2 IV design for third-KKK/hate-group indicators and county hate-crime rates, respectively, with the Table 3 controls and state-clustered standard errors. Each cross-sectional estimate uses 3,103 counties.

State homicide event study (written out from the analogous-design description on pp. 1438-1439). The main text describes a state-level event study of minority- and White-homicide rates using state exposure to the film. This schematic expression records that description; the appendix equation, fixed effects, sample, and error treatment are not printed in the main-text PDF:

$$Homicide^{g}_{s,t} = \mu_s + \lambda_t + \sum_{\tau} \beta^{g}_{\tau} \, Exposure_{s,\tau} + \epsilon^{g}_{s,t}$$

Here $g$ denotes minority or White homicide and $Exposure_{s,\tau}$ is state film penetration around release. The referenced analysis reports significant increases for minority homicide and no change for White homicide.

Survey specifications (written out from the descriptions on pp. 1453-1454). For 1946 Gallup responses, the paper regresses individual KKK knowledge and KKK-ban responses on an instrumented state-level exposure share:

$$Y_{i,s} = \alpha + \beta \, \widehat{Exposure}_{s} + u_{i,s}$$

The exposure is the share of US-born White men in a state living in screening counties, instrumented by the corresponding share living in counties with theaters. For 1970s ANES responses, the paper uses an individual-level analogue of Equation 2:

$$Attitude_{i,c} = \lambda_s + \beta \, Screened_c + X'_c \Gamma + u_{i,c}$$

The main text does not print the complete covariate list, fixed effects beyond the Equation 2 analogy, standard-error treatment, or individual sample sizes for these appendix analyses.

Causal mediation (written out from note 38, p. 1457). Long-run outcomes are regressed on klavern formation instrumented by historical theater presence, while controlling for film screening and the full covariate set. The paper notes that interpretation relies on strong assumptions, including that film screenings and long-run outcomes are exogenous conditional on historical klaverns:

$$Y_c = \lambda_s + \theta \, \widehat{Klavern}_c + \beta \, Screened_c + X'_c \Gamma + u_c$$

The instrument for $Klavern_c$ is theater presence; standard errors and sample follow the underlying county IV analysis. The estimated klavern effect is scaled by the baseline effect of screenings on klavern formation to obtain an indirect effect, then compared with the total effect. The paper suggests that nearly all long-run effects are mediated this way; numerical mediation estimates are in the online appendix.

Datasets used

Dataset	Role in paper	Wiki page
Hand-collected newspaper screening data (newspapers.com, newspaperarchive.com, Library of Congress; 6,266 ads, 1914-1919)	Primary treatment variable: county-level first-screening dates; 621 screened counties	No page yet (hand-collected; see introducesData)
Historical American Lynching Data Collection Project (“Project HAL”); supplemented by Seguin and Rigby (2019) for non-Southern counties	Short-run outcome: lynching indicator, weekly county panel 1913-1922	No page yet
Race riot records from Gilje (1996) and Red Summer Archive (visualizingtheredsummer.com)	Short-run outcome: race riot indicator, weekly county panel 1913-1922	No page yet
Kneebone and Torres (2015) KKK klavern location data	Long-run outcome: second-KKK klavern presence by 1930; intensive margin klaverns per capita	No page yet
House Un-American Activities Committee reports, compiled by Mazumder (2018)	Long-run outcome: third-KKK klavern presence, 1960s	No page yet
Southern Poverty Law Center Hate Map (2000-2019)	Long-run outcome: active hate group presence by type (KKK, White supremacist, other)	No page yet
FBI Uniform Crime Reports hate crimes, compiled by Kaplan (2020)	Long-run outcome: hate crimes per 100k residents by victim group, 2000-2018	No page yet
Theater location data (Klenotic / mappingmovies.unh.edu 1910; cinematreasures.com)	Instrument: county theater presence in 1914	No page yet
1910 US Census and 1906 Census of Religious Bodies	Demographic, social-capital, and economic controls	No page yet

Sample: 3,103 US counties, continental United States. Event study runs at weekly frequency, 1913-1922. Cross-sectional IV uses 1910 pre-treatment characteristics and outcomes measured at 1930 (KKK), 1960s (third KKK), 2000-2019 (hate groups), and 2000-2018 (hate crimes).

When to read the full paper

Read the original if you are: examining the causal effects of entertainment media on political and social outcomes; studying the origins and geographic persistence of KKK formation; applying staggered event-study or IV designs to county-level historical data; or researching the long-run transmission of racially charged organizations and institutions. Table 4 (p. 1446) contains the main IV estimates; Tables 5 and 6 (pp. 1454-1455) contain long-run hate-group and hate-crime results. Section V (mechanisms, pp. 1452-1453) is the most speculative part of the paper. Yanagizawa-Drott (2014) is the closest design precedent.

Attribution and rights

Source: peer-reviewed, American Economic Review 113(6), June 2023. Published by the American Economic Association. No open-access license detected (Crossref metadata, AEA publisher site, and OpenAlex all confirm paywalled). This distillation was initially extracted on 2026-06-24 and updated on 2026-10-04; it is not human-verified or independently reproduced. Extract-only: the PDF is not hosted here.

Ang, Desmond. “The Birth of a Nation: Media and Racial Hate.” American Economic Review 113, no. 6 (June 2023): 1424-1460. DOI: 10.1257/aer.20201867.