The Texas Constitution requires that state House of Representative districts be apportioned to the various counties. In other words, districts must be wholly contained within populous counties, and multi-county districts may not cut counties unless mandated to do so by federal law. In general, federal courts are likely to strike down a district if the most populous district is 10 percent more than the least populous district.
To calculate how many districts a county is entitled to, one must first calculate the ideal district size. The ideal district size for the House map is the state population from the census divided by 150. (Note that redistricting is based on pure population, even though children, non-citizens, and convicted felons cannot vote). In general, each district can be no more than five percent above or below this ideal district size.
To calculate how many districts a county is entitled to, simply divide the county population by the ideal district size.
Note, even areas that grew in population (like Dallas, for example) can lose state house seats. In order to keep the number of house seats that a county has in the current map, the county must grow at the same rate as the rest of the state (16.67 percent in the most recent estimate). A county that grows less than 16.67 percent loses seats.
LSR has made this calculation with respect to the census estimates released in July, and we reprint selected results in the table below.