As Barack Obama and Hillary Clinton head toward Pennsylvania, the Keystone State has already failed to become what so many others have tried to be: Ground zero. Conventional wisdom held that, had Clinton won Iowa, the Democratic race would have come to a screeching halt. If Obama had won New Hampshire, it was all over. Barring that, Super Tuesday was supposed to decide the nominee.

None of those scenarios came to pass. In fact, even Obama wins on March 4, in Texas, Ohio and Rhode Island (he managed a win in Vermont) would have increased calls for Clinton to leave the race. When she won all three of those states, the focus turned to Pennsylvania, where the final battle was supposed to take place.

Now, though, the Obama campaign is playing down Pennsylvania, and the Clinton campaign is going along. Over the next several days, Obama will make swings through North Carolina and West Virginia. Clinton will travel to West Virginia before making a swing through Indiana. Indiana and North Carolina voters cast ballots on May 6, while West Virginia holds their primary a week later, on May 13.

So, for anyone who thought the race would be over by any of the aforementioned contests, you're in good company: Virtually everyone thought the same thing. We have five weeks to get the same impression about Pennsylvania, but given the way things have shaken out so far, both campaigns have no illusions that the contest will continue well into May, at least.

When's the first time a candidate schedules a trip to Puerto Rico? Politics Nation hopes to bring you that visit live from the scene.