The raw numbers show that Democrats have 28 of 50 governorships (56%) and 3989 of 7382 legislative seats (54%). But those numbers treat Wyoming's (pop. 515,000) governorship as just as important as California's (pop. 36,458,000) and each member of the New Hampshire House (who on average represent about 3,300 people) as no different from members of the Texas Senate (representing 758,000 each).
With all apologies to Wyoming and New Hampshire, I don't think that makes a lot of sense, so I prefer to adjust for population. Democratic governors are in charge in states with about 161 million people or 54% of the U.S. population. That's a giant reversal from prior to the November elections, when Republican executives governed 188 million people or 63%. However, you only have to go back to early 2003, before the recall that booted Gray Davis from office in California, to get to the last time Democrats had the population edge.
Legislatures are a bit more complicated, but here's the method I think works best: Each legislative house should count for half the state's population.
So, you calculate the percentage of seats each party has in a house, multiply it by the state's population, then divide by two. Then, you can add each party's Senate and House totals together to get the population the party represents.
Using this method, Democratic legislators now represent 155.7 million Americans or 52.5% percent of the population, compared to 49.9% prior to Election Day (I've excluded unicameral, non-partisan Nebraska). So, adjusting for population slightly diminishes the Democratic advantage in both legislatures and governorships. It's also clear that Democrats gained a lot more ground in governorships than legislatures. The states where Democrats performed best in legislative elections, proportional to their population, were New Hampshire, Minnesota, Wisconsin, Washington and North Dakota.
If you follow legislative politics, however, you know what matters most is which party is in the majority. For example, Democrats only gained three seats in the Indiana House, but, because they now have a 51-49 edge, big changes are expected. Democrats picked up two seats in the Hawaii House, but I doubt they'll be a big difference between the old 41-10 House and the new 43-8 one.
Just looking at the places where a party has complete control, meaning both legislative houses and the governorship, Democrats control 15 states, with 73.8 million people, and Republicans are in charge in ten, with 67.2 million people. That means that more Americans (close to 158 million) reside in places with divided state government than in the Republican-controlled and Democratic-controlled states combined.
These figures, however, fail to acknowledge that not all divided government is the same. Republicans have a lot more power in a state where they have the governorship and one legislative house than one where they just have one house, but both those scenarios are considered "divided." To remedy this situation, let's say that governors have 50% of the power and that each legislative house counts for 25%.
Divvying up the population in divided states according to that formula, the result is that Democrats represent 163.3 million people, while Republicans have 133.8 million. That gives Democrats 55% of the power in state government, which, a cynic might note, is the exact same percentage I would have gotten by averaging my first two percentages.
Of course, to REALLY do this project justice, I'd have to consider judicial control, account for veto-proof majorities and distinguish between weak and strong governorships. But there's only so much math a political science major can take.
