If there had been six mini-Californias in 2012, President Obama would have carried South California, which includes San Diego, the Inland Empire and Orange County. Mitt Romney would have narrowly carried Central California, which includes the southern half of the Central Valley, and Jefferson, which includes the liberal Northern California coast and the conservative interior.

The implications for the Senate are obvious: 10 new Senate seats, four of which would almost certainly go to Democrats. The other six would be competitive, especially in presidential election years. If Democrats and Republicans were to split the six competitive seats, Democrats would net four seats in the Senate. That would give Democrats a 62-48 advantage in the Senate but push Democrats only one seat closer to a filibuster-proof majority, which would now require 66 seats.

Today’s Californians would go from being the most underrepresented by the Senate to slightly overrepresented. The people of Jefferson would probably become America’s most overrepresented citizens — just 949,000 people in possession of two competitive Senate seats, a competitive House seat and three competitive electoral votes.