Washington (CNN) In the nearly two decades between 2000 and 2018, more than 100 counties across the United States saw their white population slip under 50%, according to a Pew analysis of census information, the latest in a series of data points that make clear the country's demographics (and, eventually, its politics) are in a period of considerable change.

With the addition of the 109 counties that turned from majority white to majority non-white over the last 18 years, there are now 293 non-white majority counties in the United States. While that accounts for only 9% of the total counties in the United States, it's the change over time that is most interesting -- and where it's happening.

Two facts stand out in that regard:

1) While 109 counties went from majority white to majority non-white over the past 18 years, just two -- yes, TWO -- went from majority non-white to majority white. (They were Calhoun County in South Carolina and West Feliciana Parish in Louisiana.)

2) Some of the largest counties in the country are changing the fastest. As Pew concludes: "In 21 of the 25 biggest U.S. counties by population, nonwhite groups together make up more than half of residents. Eight of these counties were majority white in 2000 but are no longer: San Diego, Orange, Riverside and Sacramento (all in California), plus Clark (Nevada), Broward (Florida), Tarrant (Texas) and Wayne (Michigan)." And there are a handful of other huge counties (Fairfax in Virginia, Pima in Arizona, Milwaukee in Wisconsin) where the white population has sunk under 52% -- and could well go majority non-white in the next few years.