This commentary originally appeared on The Hill.
Swing states do not swing forever.
Some states will oscillate between elections for decades. Other states, will become solidly red or blue in just a few election cycles. Connecticut switched between parties in presidential elections five time between 1932 until it become solidly Democratic after 1992. Likewise, New Jersey, California, Oregon and Washington all swung four times between 1932 and 1992, then each became a Democratic state.
Arkansas and Louisiana, unlike most other southern states, were still swingable into the 1990's before becoming uncompetitive Republican spectators to the national electoral drama.
By "swing states," I am referring to the nine or ten perennial campaign battleground states that have, since 1988, been decided by less than five percentage points in the majority of elections, are usually bellwethers mirroring the national vote in those elections, and which have flipped between Democrat and Republican victories.
Colorado, Florida, Iowa, Nevada, New Hampshire, New Mexico, North Carolina, Ohio and Virginia stand as swing states today.
Recently, the most remarkable swing state to stop swinging was Missouri – the ultimate bellwether of the nation for most of the 20th century. It was competitive 24 out of 26 elections from 1904 to 2008. McCain in 2008 barely won the state, and after Mitt Romney won the state in 2012 by 10 percent. Missouri has shown no signs of swinging again.
Trump now leads there by double digits. In several ways Missouri gives some clues about the formula for shifting a swing state into a red state. What happened?
Missouri's proportions of urban and rural, black and white, Catholic and Protestant, liberal and conservative values was a microcosm of the U.S. during the 20th century. But as the Missouri's rural population began to grow in the 1990s, the Democratic Party became increasingly liberal and focused on issues important to people of color and urban dwellers.
Republican campaigns became far more effective at identifying and mobilizing suburban voters and especially white evangelicals. By 2012 white evangelicals made up about 37 percent of the electorate, and three-quarters of them voted for Romney. The result was that suburban and rural voters tilted strongly enough to neutralize the Democrats' advantages in urban areas.
Missouri's changes might be starting to occur in that battleground of all battlegrounds — Ohio.