But things are different in the various states, as this chart with links from realclearpolitics.com shows.
Let's look at it as I'm doing, preparing for Fox News's election night broadcast, by focusing on the states in the order of poll closings (all times eastern).
The first state to close is Georgia, at 7 p.m. Barack Obama has a clear lead here; about half the voters will be black, as in South Carolina, and they're going heavily for him. That will give him 30 delegates statewide and 36 delegates in the congressional districts (CDs) whose populations are more than one-quarter black (1, 2, 4, 5, 8, 12, 13); Clinton has a chance of winning 21 delegates. (For delegate allocation, you can check the invaluable Green Papers.) Republicans have a close three-way race here. Romney needs to win the high-income Atlanta suburbs (I'll be looking at the Cobb, Fulton, Forsyth, and Cherokee County returns); McCain needs to stay even with or ahead of Mike Huckabee in south Georgia, as he did in most of South Carolina.
A slew of states have 8 p.m. poll closings:
Alabama. The black percentage in the Democratic primary will be somewhat lower here than in South Carolina and Georgia; polls show the race very close. Romney is not as competitive here as in Georgia, as there is not nearly as big an affluent suburban vote. Huckabee looks to be competitive with McCain, who has been leading in the polls by varying margins. Alabama Republicans have something like proportionate representation (you need 50 percent to get winner-take-all in CDs), so McCain will have to get lucky to get a big delegate edge.
Connecticut. There seems to be an Obama trend here, but with proportional representation statewide and by CD, neither is likely to come out with much of an advantage. McCain seems to be in solid shape here, and it's winner-take-all.
Delaware. No polling here since October, so check out the New Jersey polls for hints. Looks like it'll be close for the Democrats; McCain will win on the Republican side.
Illinois. Obama will win in a landslide, and given the solidarity of his support from le tout Chicago, he should have an overwhelming share of delegates (who I believe are elected separately). McCain seems well ahead among Republicans. I predict Illinois will be called for both parties promptly at 8 p.m.
Massachusetts. Despite Ted Kennedy and John Kerry, Obama is far behind here. McCain is far ahead. Another 8 p.m. call.
Missouri. I find Missouri the most tantalizing of the Super Tuesday states, because I would not have predicted where the polls are now. Obama is running even with Clinton in a state that is 12 percent black and in which there are still a lot of Democratic primary voters in rural counties who identify themselves as moderates or even conservatives. The returns in black-majority St. Louis city are notoriously late (how many votes do you need?); note that suburban St. Louis County (which has a much larger population) is 20 percent black, which means 30 to 40 percent of Democratic primary voters there will be black. Missouri is another three-way race on the Republican side, with Huckabee doing best in southwest Missouri, which has many evangelical and born-again Christians.
I'll weigh in on the other states later.
By Michael Barone