You can find the results of past federal elections from several government sources.
The Federal Election Commission releases the official results of federal elections. These reports are run by state, every two years, and are available for elections from 1982 to 2016. They include primary, runoff, and general election results for:
U.S. House of Representatives
U.S. president (for years when there is a presidential election)
See the electoral college votes by state for past presidential elections.
Find statistics from every federal election since 1920. The results are listed by state and include Washington, D.C. and the U.S. territories. They show the official vote count for each candidate running for federal office.