The wait is almost over for Pennsylvania's Democratic presidential primary Tuesday, but voters may have to wait a little longer to find out who won the most delegates to the party's national convention.
As in other Democratic contests, Pennsylvania awards delegates based on the statewide vote and the vote in individual congressional districts.
Unlike most states, Pennsylvania has a large number of counties split into multiple congressional districts. That could delay results by a day or more as election officials work to assign votes to the appropriate districts.
Barack Obama and Hillary Rodham Clinton are vying for 158 delegates.
Fifty-five will be awarded based on the statewide vote, which should be available Tuesday night. Another 103 delegates will be awarded based on the vote in individual congressional districts. All delegates will be awarded proportionally, as they are in every Democratic contest.
The distribution of delegates among congressional districts raises the possibility that one candidate could win the statewide vote and the other could win more delegates, but the statewide vote would have to be very close.
The delegates are weighted heavily toward urban and suburban areas because Pennsylvania, like other states, apportions congressional district delegates based on Democratic voting strength in the most recent presidential and gubernatorial elections.
Under the formula, the 2nd Congressional District, which includes part of Philadelphia, has nine delegates at stake, more than any other district. The 9th Congressional District in the south central part of the state has the fewest, with three delegates at stake.
Other urban and suburban districts near Philadelphia and Pittsburgh have seven delegates at stake, while more rural districts have four or five delegates.