Hey, I got a tip last time! Woo! Anyway, here's the rest of the section on Congress. Next time, kooky and/or cool people from Congress!
2006 was the first election in which every Congressional seat held by a Democrat before was held by a Democrat after, although not necessarily the same one (i.e., everyone running for reelection succeeded, and every retiring Democrat was replaced by another); indeed, it was the first time that happened for either party. That did not quite happen in 2008, but four of the five seats captured by Republicans were held by Republicans in 2006, and Democrats still increased their majority in the House by double digits.
1994 was the first election in well over a century which the Speaker of the House was defeated for reelection. However, while Dennis Hastert was reelected in 2006, he resigned his seat a year later, which was taken by a Democrat in the special election, and Bill Foster was reelected in 2008, though Bob Dold replaced him in 2010.
Congress is often derided for having very high retention rates, but that's really not all that accurate. On average, the Senate changes half of its membership every ten years: the Senate rosters from 1999 and 2009 have 52 members in common, and 1989 and 2009 have 25. The House is similar, though the interval is 8 years rather than 10.
On the one hand, there's the pair of Strom Thurmond (R) and Fritz Hollings (D), who served together in the Senate from South Carolina from 1966 to 2003 (replaced by, respectively, Lindsay Graham and Jim DeMint, both Republicans, though of decidedly different ideological perspectives -- Graham feels that considering the other point of view is worthwhile, and occasionally works with Democrats, whereas, DeMint is of the opinion that anyone who doesn't vote against everything Democrats propose is insufficiently conservative.). On the other, Jesse Helms (R) represented North Carolina from 1973 to 2003, alongside Sam Ervin (D), Bob Morgan (D), John East (R), Jim Broyhill (R), Terry Sanford (D), Lauch Faircloth (R), and John Edwards (D). Ervin served the last two years of Clyde Hoey's second term and three of his own, East and Broyhill together served one term, and the rest had one term each. From 1974 to 2010, that seat changed parties at every election, but Richard Burr managed to beat State Treasurer Elaine Marshall and keep his job.
Delaware has only ever had one House seat. However, after the Census of 1810, it had two seats in the House, both elected from an at-large ticket, and it lost the second seat after the next census. Having one district elect multiple representatives, or having some representatives elected from the state as a whole, was not an uncommon practice in the nineteenth century. It became decidedly less common in the twentieth century, and in 1967, Congress passed a law mandating one representative per district, and each voter choosing only one representative, partially in response to racial gerrymandering in the South. It's not as altruistic as it seems, however; the courts might have been spurred by Southern states effectively disenfranchising blacks and required other states to hold at-large elections for their entire House delegations, thus endangering many incumbents.
Impeachment is an inherently political process: the House can impeach the President (or any other official) for eating jelly sandwiches in bed if it wants to, though mustering up a majority vote on that would be awfully difficult. To date, the two impeachments that have taken place, both against Democrats (well, technically; Johnson used to be a Democrat, but the Democratic Parties of 1868 and 1992 are completely different entities), have not had a whole lot of basis in fact: Andrew Johnson was impeached, and narrowly avoided conviction, for having the audacity to have basically no party base and be bad at dealing with Congress to boot, and Bill Clinton was impeached, and avoided conviction less narrowly, for being a charismatic southern Democrat who was easily elected President twice.
Johnson, Lincoln's Vice President, had previously been a Democrat; during and after the Civil War, there were very few Democrats in Congress, especially the Senate, since the North was Republican and the South, at least the parts that had been admitted back into the Union, had their federal officials appointed by loyal US citizens, which again in that part of the country pretty much meant only Republicans. Naturally, the Radical Republicans controlling Congress had to find actual grounds for impeaching him; they couldn't just say “He stinks and we hate him, out!” They wrote and passed, over his veto, the Tenure of Office Act, which prevented the President from removing any official appointed by a previous President with consent of the Senate without himself getting approval from the Senate to remove that official. This was blatantly unconstitutional, as those officials serve at the pleasure of the President and lose their jobs if he wants them to, but they didn't much care. Eventually Johnson removed someone Lincoln had appointed (Edwin Stanton, Secretary of War), and confirmed that removal by replacing him with General Ulysses Grant, then General Lorenzo Thomas, and the House promptly impeached him. After that, however, they ran into a bit of trouble. See, the second step to impeachment, after the House's majority vote to impeach, is the Senate's two-thirds vote to convict and remove from office, and removing the President from office means somebody has to take his place. In that case, the person next in line was the President pro tempore of the Senate (which back then was ahead of the Speaker of the House in the succession, and also wasn't simply a ceremonial title given to the most senior member of the majority party), Benjamin Wade, who to many people was even more objectionable than Johnson. As one newspaper put it, “Andrew Johnson is innocent because Ben Wade is guilty of being his successor.” At the time, there were 27 states in the Union, thus 54 Senators, and 36 guilty votes were required to convict Johnson. He got 35 to convict, and thus stayed in office; seven Republican Senators voted against their party, and found him innocent. Of those seven, none served another term: William Fessenden of Maine died, Joseph Fowler of Tennessee retired, James Grimes of Iowa resigned due to his health (and died three years afterward), John Henderson of Missouri retired, Peter Van Winkle of West Virginia retired, Lyman Trumbull of Illinois retired, and Edmund Ross of Kansas, the key vote, was defeated.
William R. King was elected three times to the House from North Carolina in the early nineteenth century; after helping to organize the Alabama state government, he was elected by them to the Senate from 1819 to 1844 and 1848 to 1852, after which time he retired due to health problems. King nevertheless accepted the Democratic nomination for Vice President, and served 45 days in 1853. King also slept with James Buchanan, which was not unusual at the time, since beds were expensive and they were close friends; it's alleged now that King had sex with Buchanan when they shared a bed, which is naturally all that anyone remembers. Sigh.
It's very uncommon, especially nowadays, but King isn't the only one to serve in fairly high office for multiple states: Daniel Webster served both Massachusetts and New Hampshire in the House for four years each, and spent approximately nineteen years in the Senate from Massachusetts.