The census supplies the population basis, and a statutory formula reallocates a fixed House size among the states, each of which receives at least one representative. A state's gain or loss changes its delegation and Electoral College total; it does not alter the state's two Senate seats.

Reapportionment answers how many House seats a state has. Redistricting answers where the boundaries of those seats lie. A state that keeps the same seat total may still redraw districts to equalize population after internal migration, while a state losing a seat must create fewer districts.

Do not infer partisan intent from a reapportionment result alone. Population movement can transfer seats without any line-drawing choice by state officials. Political advantage enters most directly during redistricting, when the placement of voters among districts affects the conversion of votes into seats.

Video lesson: The Bicameral Congress: Crash Course Government and Politics #2