Examining all 435 congressional districts by the 2016 citizen voting age population (CVAP, 2012 – 2016 American Community Survey 5 year estimates) underscores how an expanded base contributed to the ascent of a new Democratic US House majority. To illustrate this, we ranked districts by their percentage of non-white CVAP, as a measure of their level of racial/ethnic diversity.

Top 100 Most Diverse Districts

• Before the 2018 election, only five of the fifty most diverse districts in the country were represented by a Republican Member of Congress:
  • Democrats flipped Florida 26 and 27 (16th and 29th most diverse, respectively)
  • Ballots are still being counted in Texas’ 23rd District (37th), where Democrat Gina Ortiz Jones trails Republican Will Hurd by 1,105 of 209,058 total votes cast
  • California 21 (31st) will likely remain under Republican control with David Valadao ahead by 2,014 of almost 95,000 total votes cast
  • Mario Diaz-Balart in Florida 25 (25th) is the sole Republican in this group with comfortable control of his seat, having been re-elected with over 60 percent of the vote

• Among the 51st through 100th most diverse districts, there were an additional seven that were Republican-held going into the 2018 election:
  • The total will likely be four once all contests are decided
  • Democrats flipped New Mexico 2 (77th) and California 25 (99th)
  • California 39 (65th), where Latino Democrat Gil Cisneros leads Asian American Young Kim by 941 of 207,065 total votes counted so far, will likely be a Democratic pickup

• In the 116th Congress, we expect as many as 93 of the 100 most diverse districts to be represented by Democrats:
  • Only three of the fifty most diverse districts will be Republican-held – Florida 25 (25th), California 21 (31st, likely Republican gain), and Texas 23 (37th)
  • At least four of the districts ranked 51st to 100th most diverse will be Republican-held—Texas 27 (83rd), Texas 22 (91st), California 22 (95th), California 42 (97th)
  • Among these seven districts, Democrats in 2018 outperformed their 2016 share of the vote by an average of 4.0 percentage points, continuing the trend established in special elections from 2017 to early 2018

Next 100 Most Diverse Districts

• Democrats enjoyed even more success among districts ranked 101st through 150th, picking up an additional five Republican-held seats:
  • Democrats flipped California 10 (104th), Texas 7 (108th), California 45 (125th), Texas 32 (135th), and California 48 (138th)
  • Georgia 7 (115th) remains too close to call, where Republican incumbent Rob Woodall leads Democrat Carolyn Bourdeaux by 419 of 280,441 total votes cast
  • All of the districts in this group have approximately 35 to 45 percent non-white CVAP

Building the Majority

• Democrats picked up an additional six seats from the districts ranked 150th to 200th most diverse:
  • Districts in the previous categories were based primarily in California, Florida, and Texas
  • There is more geographic diversity in this group, including districts in the Midwest and Mid-Atlantic—New York, Oklahoma, Pennsylvania, Virginia
  • All of the districts in this group have approximately 25 to 35 percent non-white CVAP

• We project Democrats will gain a net of 39 seats, 15 of which are ranked in the top 200 in terms of population diversity:
  • Overall, Democrats could flip a total of 42 seats, but also lost 3—Minnesota 1 and 8, and Pennsylvania 14
  • Considering all congressional districts ranked in the top 50 percent with respect to diversity, Democrats flipped control of each of the following 21 (ranked by diversity):

In total, 154 Democrats and 46 Republicans will represent the 200 most diverse districts in America in the next Congress.

Suburbia was the principal battleground in the 2018 midterm election, but it is clear that the strong Democratic base was equally responsible for the massive gains earned by Democrats in 2018 US House races. As the United States grows more diverse, the current version of the Trump-Republican Party coalition is headed for extinction, or at the very least faces an insuperable disadvantage.

Note: Vote totals current as of November 16, 2018