Data sources & methodology

Boundary geometry. All county polygons are derived from public-domain U.S. Census Bureau TIGER/Line cartographic files (1:500,000 simplified for web display). Original full-resolution geometry is preserved for any computed values such as area and centroids.

County seats & establishment dates. Sourced from the Texas State Historical Association's Handbook of Texas and cross-checked against current county government websites.

Population figures. Based on the most recent U.S. Census decennial count, with intercensal estimates where appropriate. We do not invent or interpolate figures.

Updates. Boundary data is refreshed annually after new TIGER releases. Population and editorial fields are reviewed quarterly. A changelog is maintained internally and available on request.