Voters have been heading to polling stations in 24 states

It will nearly all be over by 0400 GMT on Wednesday, when the polls close in California.

The first result to appear will be the West Virginia Republican convention, possibly around 1730 GMT, and no later than 1930 GMT.

The first big state to finish voting is Georgia, where polls close at midnight GMT.

Unless the race is close, projections of the result may well be published within half an hour.

After that, results are likely to come in thick and fast.

Comprehensive coverage

Eleven primaries and caucuses come to an end at 0100 GMT, including Illinois and Massachusetts.

The Arkansas primary wraps up at 0130 GMT.

And another batch of seven states, including New York and Arizona, call a halt at 0200 GMT.

SUPER TUESDAY: KEY TIMES 1100 GMT: Voting began in Connecticut, New Jersey and New York 1730-1930 GMT: W Virginia Republican convention result Midnight GMT: Polls close in Georgia, result due soon after 0100 GMT: Voting ends in 11 primaries and caucuses, inc Illinois and Massachusetts 0130 GMT: Arkansas primary ends 0200 GMT: Polls close in seven states, inc N York and Arizona 0400 GMT: Polls close in California Super Tuesday at-a-glance Who's backing who? Super Tuesday voters' views Send us your predictions

BBC correspondents with Barack Obama in Chicago and Mitt Romney in Boston will report on the mood among their supporters after the results come in there.

About an hour later, other BBC correspondents will report from the camps of Hillary Clinton in New York and John McCain in Phoenix.

And at the end of the night, correspondents Matthew Price and Gavin Hewitt will analyse the impact of the biggest ever Super Tuesday on the Republican and Democratic nomination races.

BBC North America editor Justin Webb will be blogging through the night.

The BBC News website will also be streaming a Super Tuesday results programme hosted by BBC World News America presenter Matt Frei, between midnight and 0500 GMT.