Ever since 1954, the best source for election returns data has been the series called America Votes. A new volume is published after each congressional and presidential election. America Votes 27 is now in print. It includes the 2006 election results. Most good libraries have the whole series. If you have access to a good library, presumably that library will soon have America Votes 27 on the reference shelf. The leader author is Rhodes Cook; the book is published by Congressional Quarterly Press.