Every 10 years, it's time for reapportionment and redistricting. The framers of the Constitution created the first regularly scheduled national census and required, for the first time that I am aware, that representation in a legislature be apportioned according to population.
Reapportionment is automatic: A statutory formula takes the Census figures and apportions the 435 House districts among the 50 states. Wyoming and six other states will each get one, California will probably get 53, and the rest some number in between.
Seven states, according to projections by Polidata Inc., will gain a House seat, and Texas will gain four -- nine states will lose a House seat, and Ohio will lose two. Overall, states carried by John McCain in 2008 will gain a net seven seats (and electoral votes), and states carried by Barack Obama will lose seven.
But that doesn't necessarily mean Republicans will gain House seats. That depends on redistricting -- how the lines are drawn by the politicians in each state (or, in a couple of cases, by nonpartisan commissions).
That's particularly true in states with large numbers of districts and densely packed metropolitan areas. You can't do much gerrymandering in a state with only a few districts. But you can in states with more than four or five.
Eighteen months ago, it looked like Democrats were going to profit from redistricting. An optimistic scenario for Democrats, extrapolating from the 2008 election results, was that if they could gain three governorships and three state senates and otherwise hold what they had, they would control redistricting in 14 states with more than five districts, including California, New York, Illinois, Michigan, North Carolina and New Jersey.
Those states are projected to have 195 districts in the House elected in 2012. Clever redistricting could move between one and two dozen into the Democratic column. That would have been the Democrats' best redistricting cycle since the one following the 1980 Census.
But that scenario now is the stuff of dreams. Democrats are threatened with losing many governorships and legislative chambers, and their chances of taking over many from the Republicans look dismal.
Instead, the optimistic scenario belongs to the Republicans. If they hold what they have and capture a few governorships (Ohio, Tennessee, Wisconsin) and a few legislative chambers (the Houses in Indiana, Michigan, Ohio and Pennsylvania, and both houses in Wisconsin), they will control redistricting in 11 states with more than five House seats, including Florida, Georgia, Michigan, Ohio, Pennsylvania and Texas. Those states are projected to have 178 House seats.