<p>This paper introduces a database of electoral precinct-level election returns for Mexican municipal elections between 1994 and 2019. This database includes: (i) electoral precinct-level votes for each electoral coalition, the coalitions of the incumbent mayor and incumbent state governor, and the four most popular political parties; (ii) electoral precinct-level valid and total votes, the number of registered voters, and turnout; (iii) the partisan composition and municipal-level votes of the incumbent and runner-up electoral coalitions from the previous election; and (iv) the partisan composition of the state-level incumbent governor. This paper outlines the organization of this data, its sources, and key variables, and describes the processes used to standardize the data. This database has the potential to support the cross-sectional and longitudinal study of local Mexican elections over two decades using fine-grained precinct-level electoral returns that enable panel and regression discontinuity analyses.</p>