April 24, 2018
This New York Times page should be a good source of results from the special election for Arizona's 8th congressional district. Polls close at 10:00 PM Eastern Time; the first results expected around 11:00 PM. According to the Secretary of State, these first results will be from early voting. This is expected to be a majority of the vote in the election, so it is possible we'll have an idea of the outcome at that time. Subsequent results - today's voting - are not expected until midnight or later.
See our article from earlier Tuesday for more information on the election.