One of the side effects of low turnover in Congress is that politicians who were involved in historic decisions tend to stick around for a while.
Take Martin Luther King Jr. Day, for example. The holiday is the result of House approval in August 1983 and a Senate vote that October. President Ronald Reagan signed it into law in November that year.
Twenty-six members of Congress at the time are still there, although nearly half have moved across the Capitol from the House to the Senate. It's worth pointing out that the 98th Congress, which approved the measure, was substantially more white than the current one (which is heavily white but still the most diverse in history).
The vast majority of lawmakers who voted against the measure were white, but one Hispanic member, Rep. Manual Luján (R-N.M.) voted against it.
Six current members of Congress were among those voting "no" in the 338-90 House vote and 78-22 Senate tally. Two, John McCain (R-Ariz.) and Richard Shelby (R-Ala.) moved from the House to the Senate in the interim. (Shelby was a Democrat when he voted against MLK Day.) McCain apologized for that vote when he ran for president in 2008.
Twenty current members supported it. They include Sens. Thad Cochran (R-Miss.) and Patrick Leahy (D-Vt.) and 10 who moved from the House to the Senate. That list includes Sens. Barbara Boxer (D-Calif.), Harry Reid (D-Nev.) and Pat Roberts (R-Kan.).
Notice how many more non-white members of Congress there are now. It's still not representative of the American population (and is actually diversifying much more slowly), but it's clearly less white.
There's one member of the current Congress who didn't even exist at the time of the vote. That's Rep. Elise Stefanik (R-N.Y.), who is the youngest woman ever elected to Congress. She was born in 1984.