Flight of the graybeards: The next Senate will be the greenest in decades (Interactive)

Chris Wilson

When Max Baucus announced on Tuesday that he will retire from the Senate in 2014, he queued up in the long line of veteran senators to leave the upper chamber since President Obama took office.

The flight of the old-timers is neatly captured by a pair of simple statistics: When the 110th Congress convened on Jan. 3, 2007,the 100 senators had a combined 1,328 years of experience in the United States Senate. When the 113th Congress convened last January, that figure had fallen to 1,040.

Baucus, D-Mont., is the sixth veteran Democratic senator to head for the exits rather than run for reelection next year. Even if every other current senator stays put, the 114th session of the Senate will have fewer than 1,000 combined years of incumbency for the first time since 1985.

New candidates for Congress routinely cast their opponents’ tenure in Washington as a negative, and run on the fiction that one can be a useful lawmaker without participating in the legislative process. To those sympathetic to this view, the current trend should be welcome news.

The following interactive visualizes the total years of experience in the Senate and the House of Representatives for every year since the founding of the country. Use the blue button to toggle between chambers, and use the red button to switch the y-axis to a “per lawmaker” measure of experience, to correct for the fact that earlier congresses had fewer people.

The peak Senate tenure in 2007 is a particularly impressive statistic given that 12 of those 100 senators had just been elected to the chamber in the previous election. If you switch to the House view, you see a much more responsive graph, with huge dips after Watergate and during President Bill Clinton’s first term. That makes sense; a senator has a two-in-three chance of dodging a politically toxic year for congress, like 2006 or 2010,while House members have to face voters every two years.

If you study the graph of Senate tenure carefully, you can also see a significant dip in the early twentieth century as states moved to direct election of senators—a policy enshrined in the 17th amendment, adopted in 1913.

The departure of veteran senators will make room for a new generation of committee chairs and dealmakers. Whether they hang around as long as their ancestors will have a lot to do with how much voters choose to punish experience at the polls.

The data for this interactive is based on previous terms served by each member on the first day of every session of congress, so figures may slightly over count those who served partial terms. Want to see how it's done? The source is on GitHub.Questions and comments? E-mail me at cewilson@yahoo-inc.com