In what is likely the most divisive election in recent history, deep-rooted patterns in how the country votes have become more pronounced.

The majority of counties with populations greater than 500,000 — where roughly half of Americans live — swung further to the left. In Los Angeles County, for example, about 71 percent of votes went for Hillary Clinton this year, compared with about 69 percent for Obama in 2008 and 2012, and 63 percent for John F. Kerry in 2004. That effect even spilled into neighboring Orange County, which before this election had not voted for a Democratic presidential candidate since Franklin D. Roosevelt in 1936.