Millions of votes have been cast in this year's midterms, and the question after the polls close is who won. The Associated Press, which calls winners in more than 5,200 races, has explained how its Decision Team makes that call.
AP collects verified vote totals from local election officials and precincts and cross-checks them against official websites and electronic feeds. Its staff tracks county-level results, the types of ballots cast, turnout and how many ballots remain outstanding.
AP calls a race only when it is certain the trailing candidate cannot overtake the leader. A race still being tabulated is "too early to call." A race can be "too close to call" only after tabulation is complete and the margin is still too small to determine a winner. AP says it does not make projections, does not rely on other outlets' calls and does not act on a candidate's concession.
In practice, different states count early and mail ballots at different speeds, so some results come in quickly while others take days. A call means the outcome is clear, not that every ballot has been counted.
Polls in Tennessee close at 7 p.m. Central on Tuesday.
Sources: Associated Press, WBUR, PBS NewsHour