Confusion on swearing-in dates

I'm doing a project for work at Project Vote Smart that requires the exact dates that senators and representatives took office. Finding the information was surprisingly difficult, and actually somewhat annoying.

After some rifling around on the official House and Senate pages, I found the definitive sources. The house has a biographical search that's pretty handy, and the Senate has a chronological list of everyone who has served (disclaimer: the list is a .pdf that crashed my browser twice). Now I find these pretty handy, but it didn't help my cause much that these analagous lists were organized so differently.

I thought for sure it would be on Congresspedia.org, but it wasn't. Later I added the information to former Rep. J.D. Hayworth's page as an example of where I think it should go.

While I usually defend Wikipedia, it was the worst resource of all for this project. While most sources, including Congress itself, consider senators and representatives to have taken or left office on the days of swearing-in (often January 3), Wikipedia cites the day Congress convenes. Again using the example of Hayworth, compare his official Congressional biography with his Wikipedia entry.

I am reticent to edit that page, because it could end up more of a mess if it loses internal consistency. But I highly recommend adding swearing-in dates to pages on congresspedia.