A map of all of the U.S. congressional districts (as of the 110th Congress).  To find the district's number, look at the district, compare with the color code below to get number.
Built upon Image:US Congressional Districts color.svg, created by me
Mr. Matté (if there is an issue with this image, contact me using this image's Commons talk page, my Commons user talk page, or my English Wikipedia user talk page; I'll know about it a lot faster)