At 2 p.m. on Tuesday, when the Republican National Convention reconvenes after taking a recess for Tropical Storm Isaac, the first order of business will be officially to nominate Mitt Romney.
Romney is nominated through a roll call, in which each state plus American-held territories will vote for the candidate. When Romney hits 1,144 votes, he will have officially clinched the GOP nomination for president. The order of the voting will proceed alphabetically, which means that theoretically, Missouri will be the state to put Romney over the top. After Missouri has voted, 1,148 votes will have been submitted.
It is possible that some delegates will abstain, or will vote instead for one of the candidates who has dropped out of the race, meaning that it's possible the 1,144 threshold will be pushed back, beyond Missouri.
It's not uncommon for the delegation from the candidate's home state to be the one to put him over the required delegate threshold. In 2008, Arizona delayed its vote so that it could be the one to make Sen. John McCain the nominee.