Ohio has decided elections before, but this is a first at deciding the nomination. It has 91 pledged delegates proportional to each congressional district (also 70 “Super Delegates”). Some districts are “more equal” than others.

The Chicago Tribune political blog, The Swamp, has the skinny.

* The most delegate-heavy district in the state is the 11th CD, on Cleveland’s east side. It is represented by Rep. Stephanie Tubbs Jones, a prominent Clinton supporter — but its demographics skew heavily toward Obama, including a large African American population. Eight delegates are at stake; experts say Obama could win at least five.

* Several districts have an odd number of delegates — meaning the winner is guaranteed to gain at least a one-delegate advantage there. They include the 17th, which encompasses much of the struggling areas around Youngstown – which has already drawn visits from both Clinton and Obama – and the 6th, the former district of Ohio Gov. Ted Strickland, another prominent Clinton supporter. The odd-delegate districts are clustered in southeast Ohio, so expect to see candidates spend a lot of time there.

* Relatively fewer delegates are up for grabs in the two districts that slice through Columbus, the capital and the home of television’s Keaton family, whose suburbs are always a key general election battleground. But the Columbus media market reaches into several other districts beyond the metro area limits, which explains why we’ve seen plenty of political ads on television here already tonight.

* Six delegates are on the line in the 9th congressional district, which includes the city of Toledo and your Swamp correspondent’s favorite Ohio restaurant: the legendary Hungarian hot dog joint, Tony Packo’s.

Go get ‘em, candidates!