The very first speaker of the House was Pennsylvanian Frederick Augustus Conrad Muhlenberg. He was elected speaker on April 1, 1789, less than a month after he joined the body. No speaker of the House since has been elected to the position with less experience in the body.
But, of course, Muhlenberg had a disadvantage: The House was only about a month old, too. The Constitution had been ratified only about 560 days prior, mind you, so this was not an unreasonable situation.
As John Boehner steps down from his position at the end of October, the man poised to replace him is Rep. Kevin McCarthy of California. McCarthy has been in the House far longer than Muhlenberg, having been been sworn in in 2007. But by recent speaker standards, he's practically a freshman.
The past 20 speaker have been elected to the position with far more experience than those that had preceded them. Besides Muhlenberg, the speaker with the least experience in the House was Henry Clay, elected after less than a year in the body (but after his having served in the U.S. Senate). The speaker with the most experience was John McCormack, who'd already been there for over three decades when he took over.
You can see from that chart that more recent speakers, those on the left side of the circle, have served longer. Part of that is that average length of service in each body has increased over time, and part is due to the emphasis on seniority. The past 20 speakers have been in the House for an average of 8,492 days before being elected. Boehner had been in for 7,306. McCarthy will be at 3,223 -- the least experience in the House since Georgia's Charles Frederick Crisp in 1891.
We've also added in Rep. Dan Webster (R-Fla.) who also plans to run for speaker. Having been in the House since just 2011, he'd be the least-experienced House speaker since Ohio's Joseph Warren Keifer in 1881.
After Boehner's resignation, there's no way that any member of the House that could beat the all-time least-experienced record. If the House were to elect Rep. Darin LaHood (R-Ill.), sworn in only 11 days ago, he'd still have three weeks on Muhlenberg by that point. Of course, there's no requirement that the speaker be a member of the House. So by electing an outsider -- say, perhaps, a New York real estate mogul? -- the 114th Congress could set an experience record that could never be broken.