Critical Counties is a CNN series exploring 11 counties around the country that chief national correspondent John King has identified as key in the 2016 election. These counties could play an outsize role in the election and offer an instructive example of what the political parties have accomplished. Prince William County is the seventh county in the series, which runs through Election Day. Explore the other critical counties.

The country is changing, and so is its electorate.

As its older, whiter population ages and immigrant populations settle down, the United States will grow more diverse. Gradually, some Republican strongholds can become competitive. Prince William County, Virginia, is one such place.

A very wealthy suburban county in the traditional swing state of Virginia, Prince William County once voted Republican. But over the past 15 or so years, its population has changed. Wealth and diversity have flourished outside of Washington, DC.

Prince William County has become a majority-minority district, voting largely Democratic for the past few cycles.

Signs bode well here for Hillary Clinton. Not only is it lacking the white working-class populations on which Donald Trump has built his base, it is also home to a disproportionate number of government workers who are quite familiar with her running mate, Virginia Sen. Tim Kaine. The Democratic vice presidential nominee is a Virginian who speaks Spanish, like a lot of Prince William County residents. According to data from Google Trends, Prince William County was the top county searching about immigration and the phrase "en ingles."

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