St. Louis (KSDK) -- Voters are being warned to prepare for long lines when they arrive at their polling location.
Polls opened in Illinois and Missouri at 6 a.m. Tuesday and will remain open until 7 p.m.
Voters will select the next president and have a chance to vote on several state and local races.
Voter turnout in both states is expected to approach record levels.
Some Illinois voters have already cast their ballot because the state allows early voting.
Missouri voters can find their polling location by visiting the KSDK Missouri Voters' Guide.
Illinois voters can find their polling location by visiting the KSDK Illinois Voters' Guide.