How closely do U.S. legislators match the demographic profile of those they represent? It’s closer than it was 30 years ago — but not by much. For example, after the “Year of the Woman” in 1992, only 1 in 10 members of the U.S. Congress was a woman. In the current session, fewer than 3 in 10 members of Congress are women.

Black representation in Congress has changed even more slowly. In 1993, Congress had 40 Black voting members. That has ticked up to 54 today, a shift from 7 percent to 10 percent of Congress over nearly three decades. At that pace, it would take at least another 30 years — until 2050 — for women and Black Americans to be represented in Congress to equal their respective shares of the U.S. population. That’s true for other racial and ethnic groups and for women of color, as well.

Previous scholars have found that any such changes are shaped many months before an election, when party officials recruit candidates to run for office. Republican candidates tend to be White and male more often than Democratic candidates; as a result, Congress’s diversity tends to increase when Democrats have a good electoral year. What does our data portend for 2021 and beyond?

Look at state legislatures now to see what Congress will look like in the future

We look to trends in state legislatures to answer this question. State legislatures are a sort of training ground for future members of Congress. Nearly half of all U.S. Senate and House seats are held by former state legislators. This includes well-known members such as Reps. Matt Gaetz (R-Fla.), Ilhan Omar (D-Minn.), Rashida Tlaib (D-Mich.) and Steve King (R-Iowa) and Sens. Marco Rubio (R-Fla.) and Charles E. Schumer (D-N.Y.). Looking at the states can help us forecast what our national politics may look like over the next decade or more.

Americans vote based on party

We have been tracking general election candidates for office in 21 very different state legislatures for nearly a decade, ranging from Arizona to New York to West Virginia. With that data, we can see that Republicans and Democrats have different approaches to recruiting and supporting female candidates and candidates of color. Since 2012, women have made up an increasing share of candidates for our 21 state legislatures, jumping in less than a decade from roughly 25 percent to 35 percent. But the vast majority of those have been Democratic women. In fact, during that time, women have gone from making up about 30 percent of Democratic state legislative candidates to 47 percent — already at near parity with their share of the population. By contrast, this year only 22 percent of Republican state legislative candidates are women, just a slight increase from 18 percent in 2012.

The same is true for candidates of color. Since 2012, candidates of color have gone from making up roughly 17 percent to 22 percent of state legislative candidates. But once again, that’s almost entirely because they’ve made up a larger share of Democratic candidates. In our states, candidates of color have gone from making up 28 to 36 percent of Democratic state legislative candidates. In the Republican Party, that increase has been much smaller — from 7 percent in 2012 to 9 percent this year.

White non-Hispanic Americans make up about 60 percent of the U.S. population — which is quite close to their current share of Democratic state legislative candidates in these states.

While perhaps not surprising, the demographic contrast between the parties is striking. One party’s candidates are rapidly starting to resemble the United States population. The other’s do not.

Given that, we should expect more demographic change in state legislatures and in Congress in Democratic “wave” years. That was certainly true in 2018, when voters sent an infusion of new Democratic members to state legislatures and Congress, visibly increasing the numbers of women and people of color across the board. At this point, it looks as if 2020 is likely to be another Democratic wave election. If that does happen, we expect our state legislatures and Congress to look demographically more like the United States next year than they do right now.

When candidates of color run, they win

What does this all mean? Our research suggests that diverse candidates of both parties do well when voters are given a partisan choice. Research on female candidates finds that when they run, they win as often as men do. Similarly, we have found that when candidates of color run, they are just as likely to win. Even in majority-White electoral districts, candidates of color and women of color win general elections if they are from the district’s favored party. Then-Sen. Barack Obama (D-Ill.), Sen. Ted Cruz (R-Tex.), Sen. Marco Rubio (R-Fla.), Sen. Tim Scott (R-S.C.), Sen. Cory Booker (D-N.J.) and former representative Mia Love (R-Utah) all won election in majority-White states or districts.

This does not diminish the severe and unfair disadvantages of running as a woman or person of color in elections with sexist and racist voters and opponents. But our data show very clearly that candidates systematically overcome these barriers to win U.S. office.

There is a growing body of scholarship focusing on what prevents candidates of color from winning office. Our results at the state level demonstrate that one solution is that the parties can recruit and support more diverse candidates to run in the first place.

Research suggests that we should be optimistic about voters’ support for minority and female candidates — perhaps even more optimistic than party operatives themselves. Our data indicate that any “blue wave” election is likely also to bring a broader demographic into office for years to come.

Eric Gonzalez Juenke is an associate professor of political science and Chicano/Latino studies at Michigan State University, where he studies candidates, elections and their effects on representation in the United States.

Paru Shah is an associate professor of political science at the University of Wisconsin at Milwaukee, where she studies candidates of color and female candidates as they seek and attain office.

Bernard L. Fraga is an associate professor of political science at Emory University and author of “The Turnout Gap: Race, Ethnicity, and Political Inequality in a Diversifying America” (Cambridge University Press, 2018).

Erika Vallejo is a PhD student of political science at Michigan State University, where she studies working-class candidates, race, gender and immigration in the United States.