New evidence suggests that electoral fraud persists in Mexican elections despite the country's democratic progress.

This study analyzes voter turnout patterns across polling stations grouped by childhood surnames during 2010 gubernatorial races.

Data & Methods: Using surname-based polling station assignment creates a unique test for election integrity, as voters with similar names shouldn't influence political outcomes.

* Examines all local elections in Mexico from 2006-2015

* Focuses specifically on the 2010 gubernatorial contests

* Leverages the unusual electoral system where polling stations are grouped by surname

Key Findings: Sharp drops in turnout occur at state boundaries within polling station groups, pointing to systematic fraud.

* Fraud is detected through unexpected discontinuities in voting patterns across contiguous precincts

* This finding contradicts claims that corruption has been eliminated from Mexican elections

* The results show fraud remains concentrated in specific areas or 'enclaves'

Broader Implications: These findings highlight challenges to Mexico's democratic transition, indicating fraud is still prevalent and organized.