Back in 1990, Democrats controlled 60 percent of all state legislative seats in the United States, along with nearly three-quarters of the nation's state Houses and Senates.

Today, they control less than half (47 percent) of all seats and just 41 percent of the chambers.

What happened in between? Well, the South steadily turned red, for one. In addition, the GOP waves of 1994 and 2010 and the Democratic waves of 2006 and 2008 both registered big at the state level.

Below is a look at how the lower and upper chambers in each state progressed between 1990 and 2011.

(For the latter years, the data is from March of the year after the election, so the 2010 election results aren't reflected until 2011. The data don't include the 2012 elections, in which Democrats regained a fair amount of lower-chamber seats.)

Here are the lower chambers (state Houses, assemblies, etc.):

And the upper chambers (state Senates):

Note: Nebraska is not shaded on either of these maps because it has both a unicameral legislature (i.e. only one chamber) and its elections are technically nonpartisan.

Data is courtesy of the National Conference of State Legislatures and the Kaiser Family Foundation.