Two Iowa counties an hour apart show America’s growing political divide

Kim DeVore was an enthusiastic supporter of Barack Obama when he ran for president in 2008, drawn to his message about bringing the country together. A loyal Democrat, she caucused for him and even traveled to Des Moines to attend a rally he held there.

But DeVore, who lives in a tiny Iowa town near the Missouri border, eventually came to feel that Obama had only divided the country further. She changed her party registration to Republican in 2016 and voted for Donald Trump, drawn to his pledge to build a wall...