This study examines the extent to which local incidents of political violence reshape political competition. Specifically, the extent to which they influence party system fragmentation. It draws on data from over two thousand municipalities in Mexico across three consecutive elections (2018, 2021, and 2024), as well as on a series of generalized least squares models with random effects and clustered standard errors. These show that political violence significantly suppresses party system fragmentation, and that this suppressive effect intensifies over time. The study argues that political violence functions as a ‘shadow institution’ that mimics the effects of formal electoral rules by altering the costs, risks, and incentives of political participation. In all, this study highlights the need to account for both temporal dynamics and informal coercive pressures when analyzing the structure and evolution of party systems.
BaileyJTaylorMM (2009) Evade, corrupt, or confront? Organized crime and the state in Brazil and Mexico. Journal of Politics in Latin America1(2): 3–29.
2.
BanguraISöderberg KovacsM (2019) Competition, uncertainty and violence in Sierra Leone’s swing district. In: Söderberg KovacsMBjarnesenJ (eds) Violence in African Elections: Between Democracy and Big Man Politics. London: Zed, 114–134.
3.
BarberBKMcNeelyCOlsenJA, et al. (2013) Long-term exposure to political violence: The particular injury of persistent humiliation. Social Science & Medicine156: 154–166.
4.
BarnesN (2017) Criminal politics: an integrated approach to the study of organized crime, politics, and violence. Perspectives on Politics15: 967–987.
5.
BirchS (2020) Electoral Violence, Corruption, and Political Order. Princeton: Princeton University Press.
6.
BirnirJKGohdesA (2018) Voting in the shadow of violence: electoral politics and conflict in Peru. Journal of Global Security Studies3(2): 181–197.
7.
BirnirJKVan CottDL (2007) Disunity in diversity: party system fragmentation and the dynamic effect of ethnic heterogeneity on Latin American legislatures. Latin American Research Review42(1): 99–125.
8.
BlattmanCMiguelE (2010) Civil war. Journal of Economic Literature48(1): 3–57.
9.
CalderónGRoblesGDíaz-CayerosA, et al. (2015) The beheading of criminal organizations and the dynamics of violence in Mexico. Journal of Conflict Resolution59(8): 1455–1485.
10.
CanettiDHallBJRapaportC, et al. (2013) Exposure to Political Violence and Political Extremism: A Stress-Based Approach. European Psychologist184: 263–272.
11.
Caro GonzálezV (2013) Political Competition Amid Violence: Evidence from Colombia. Houston: University of Houston.
12.
CassarAGrosjeanPWhittS (2013) Legacies of violence: trust and market development. Journal of Economic Growth18: 285–318.
13.
ChaturvediA (2005) Rigging elections with violence. Public Choice125: 189–202.
14.
CONAHCyT (2024) Covid-19 México. Retrieved from Consejo Nacional de Humanidades, Ciencias, y Tecnologías. https://datos.covid-19.conacyt.mx/
15.
CoxGW (1997) Making Votes Count: Strategic Coordination in the World’s Electoral Systems. Cambridge: Cambridge University Press.
De FeoGDe LucaGD (2017) Mafia in the ballot box. American Economic Journal: Economic Policy9(3): 134–167.
22.
De JuanAPierskallaJH (2016) Civil war violence and political trust : microlevel evidence from Nepal. Conflict Management and Peace Science33(1): 67–88.
23.
Di CataldoMMastroroccoN (2022) Organized crime, captured politicians, and the allocation of public resources. Journal of Law, Economics, and Organization38(3): 774–839.
24.
DubeADubeOPonce-GarcíaO (2013) Cross-border spillover: US gun laws and violence in Mexico. American Political Science Review107: 397–417.
25.
DubeOGarcía-PonceOThomK (2016) From maize to haze: agricultural shocks and the growth of the Mexican drug sector. Journal of the European Economic Association14: 1181–1224.
26.
DuchRMPalmerHD (2002) Strategic voting in post-communist democracy?British Journal of Political Science32(1): 63–91.
27.
EsbergJ (2025) Criminal fragmentation in Mexico. Political Science Research and Methods1–8.
28.
FafchampsMVicentePC (2013) Political violence and social networks: experimental evidence from a Nigerian election. Journal of Development Economics101: 27–48.
29.
Farfán-MéndezC (2019) The structure of drug trafficking organizations and money laundering practices: a risk appetite hypothesis. Journal of Illicit Economies and Development1: 294–311.
30.
Franco-VivancoEMartinez-AlvarezCBFlores MartínezI (2023) Oil theft and violence in Mexico. Journal of Politics in Latin America15: 217–236.
31.
Fuerte CelisMd.Pérez LujanECórdova PonceR (2019) Organized crime, violence, and territorial dispute in Mexico (2007–2011). Trends in Organized Crime22: 188–209.
32.
Garzón VergaraJC (2012) La rebelión de la redes criminales: El crimen organizado en América Latina y las fuerzas que lo modifican. Washington D.C.: Woodrow Wilson International Center for Scholars.
33.
GolosovGV (2015) Factors of party system fragmentation: a cross-national study. Australian Journal of Political Science50(1): 42–60.
34.
Gómez DíazA (2022) Still learning to make votes count? Electoral coordination in Mexico’s mixed-member electoral system. Election Law Journal21(3): 229–248.
35.
Grzymala-BusseA (2010) Time will tell? Temporality and the analysis of causal mechanisms and processes. Comparative Political Studies44(9): 1267–1297.
36.
Gutiérrez-SanínFWoodEJ (2017) What should we mean by “pattern of political violence”? Repertoire, targeting, frequency, and technique. Perspectives on Politics15(1): 20–41.
37.
HarbersI (2010) Decentralization and the development of nationalized party systems in new democracies: evidence from Latin America. Comparative Political Studies43(5): 606–627.
38.
HarishSPLittleAT (2017) The political violence cycle. American Political Science Review111(2): 237–255.
39.
HunterLYBennettDJRobbinsJW (2018) Destabilizing effects of terrorism on party system stability. Terrorism and Political Violence30(3): 503–523.
40.
HunterLYRobbinsJWGinnMH, et al. (2019) Meet in the middle: terrorism and centrist party vote shares in legislative elections. Global Policy10(1): 60–74.
41.
INE (2024) Sistema de Consulta de la Estadística de las Elecciones. Retrieved from Instituto Nacional Electoral. https://siceen21.ine.mx/home
INPI (2022) Catálogo de Municipios A y B de Acuerdo a la Clasificación del INPI. Mexico City: Instituto Nacional de Pueblos Indígenas.
44.
IshiyamaJ (2014) Civil wars and party systems. Social Science Quarterly95: 425–447.
45.
IshiyamaJ (2022) Organized crime and political party systems characteristics in post-communist and Latin American countries. Journal of Elections, Public Opinion, and Parties32(4): 771–792.
46.
KjaerUElklitJ (2014) The impact of assembly size on representativeness. Journal of Legislative Studies20(2): 156–173.
47.
LaaksoMTaageperaR (1979) “Effective” number of parties: a measure with application to west Europe. Comparative Political Studies12(1): 3–27.
48.
LagoILago-PeñasS (2016) An economic explanation of the nationalization of electoral politics. Electoral Studies44: 409–418.
49.
LagoIMartínez i ComaF (2012) Forgetting to make votes count: the role of previous democratic experience. Electoral Studies31: 413–421.
50.
LeBasA (2006) Polarization as craft: party formation and state violence in Zimbabwe. Comparative Politics38(4): 419–438.
51.
LeruthBStokerG (2020) Improving the political judgement of citizens: why the task environment matters. Policy & Politics48(3): 381–396.
52.
LessingB (2021) Conceptualizing criminal governance. Perspectives on Politics19(3): 854–873.
53.
MadridRL (2012) The Rise of Ethnic Politics in Latin America. Cambridge: Cambridge University Press.
54.
MorgensternSSwindleSMCastagnolaA (2009) Party nationalization and institutions. The Journal of Politics71(4): 1322–1341.
55.
MoserRG (2001) Electoral systems and the number of parties in postcommunist states. World Politics51: 359–384.
56.
O'NeilS (2009) The real war in Mexico. Foreign Affairs88(44): 63–77.
57.
OmotolaJSOyewoleS (2023) Electoral violence in Nigeria: insights from off-cycle subnational elections. Journal of Asian and African Studies60(2): 947–959.
58.
PedersenD (2002) Political violence, ethnic conflict, and contemporary wars: broad implications for health and social well-being. Social Science & Medicine55(2): 175–190.
59.
PonceAF (2019) Violence and electoral competition: criminal organizations and municipal candidates in Mexico. Trends in Organized Crime22: 231–254.
60.
Puac-PolancoVDLopez-SotoVAKohnR, et al. (2015) Previous violent events and mental health outcomes in Guatemala. American Journal of Public Health105(4): 764–771.
61.
RíosV (2015) How government coordination controlled organized crime: the case of Mexico’s cocaine markets. Journal of Conflict Resolution59: 1433–1454.
62.
RohnerDThoenigMZilibottiF (2013) Seeds of distrust: conflict in Uganda. Journal of Economic Growth18: 217–252.
63.
RubinODIhleR (2017) Measuring temporal dimensions of the intensity of violent political conflict. Social Indicators Research132(2): 621–642.
64.
SayariS (1978) The Turkish party system in transition. Government and Opposition13(1): 39–57.
65.
SchedlerA (2014) The criminal subversion of Mexican democracy. Journal of Democracy25(1): 5–18.
66.
SingerMMStephensonLB (2009) The political context and Duverger's theory: evidence at the district level. Electoral Studies28(3): 480–491.
67.
StibbeM (2020) Coalition-building and political fragmentation, 1924-1930. In: RossolNZiemannB (eds) The Oxford Handbook of the Weimar Republic. Oxford: Oxford University Press.
68.
TaylorLK (2016) Impact of political violence, social trust, and depression on civic participation in Colombia. Peace and Conflict: Journal of Peace Psychology22(2): 145–152.
69.
TrejoGLeyS (2018) Why did drug cartels go to war in Mexico? Subnational party alternation, the breakdown of criminal protection, and the onset of large-scale violence. Comparative Political Studies51(7): 900–937.
70.
TrejoGLeyS (2020) Votes, Drugs, and Violence: The Political Logic of Criminal Wars in Mexico. Cambridge: Cambridge University Press.
71.
TrejoGLeyS (2021) High-profile criminal violence: why drug cartels murder government officials and party candidates in Mexico. British Journal of Political Science51(1): 203–229.
72.
WeintraubMVargasJFFloresTE (2015) Vote choice and legacies of violence: evidence from the 2014 Colombian presidential elections. Research & Politics2(2): 1–8.
73.
WoodEJ (2009) Armed groups and sexual violence: when is wartime rape rare?Politics & Society37: 131–161.
74.
WoodEJ (2015) Conflict-related sexual violence and the policy implications of recent research. International Review of the Red Cross96(894): 457–478.
