States are not required to use the federal census
by Peter Wagner, November 10, 2003
While states must redistrict on the basis of actual population, the U.S. Constitution does not require states to use the federal census for its own redistricting:
“Although a state is entitled to the number of representatives in the House of Representatives as determined by the federal census, it is not required to use these census figures as a basis for apportioning its own legislature.”
States are therefore free to use their own census or to correct how the federal census counts prisoners.
Bethel Park v. Stans, 449 F.2d 575, 583 (3rd Cir. 1971)