Here's a detailed story that explores why Ohio is so important in presidential (including primary) elections.
"The presidential spotlight shines on this Midwestern state every four years, and for good reason. As Ohio goes, so goes the nation — at least for the past 44 years."
http://news.yahoo.com/s/ap/20080304/ap_on_el_pr/why_ohio
Here's an interesting paragraph from the story:
"Long considered a microcosm of the nation, the state is home to an incredibly rich mix of people from every income category, education level, ethnicity and political leaning. It's all reflective of the state's geographical diversity, with eight major urban centers — Cincinnati, Columbus, Dayton, Toledo, Cleveland, Akron, Canton and Youngstown — as well as a slew of middle-sized cities, suburbs, exurbs, small towns, rural areas and tiny Appalachian hamlets in the southeast."
Though I've been a Michigander (Michiganian?) for most of my adult life, I'm still proud to be a former Oregonian (Ohio).
It just shows that Ohioians can, for the most part, get a long -- even if they don't agree.
--Mike

It could be narrowed down to northwest Ohio and not just Ohio.
November 1, 2004 Toledo Talk posting titled Northwest Ohio key to presidential election that pointed to a Columbus Dispatch article :
That northwestern Ohio has become the bellwether region of the bellwether state is remarkable because, except for Lucas County, the mostly agricultural region has a long Republican tradition. In effect, Lucas and its 11 surrounding counties cancel one another out in presidential races. Even though northwestern Ohio accounted for only 9 percent of the statewide vote in 2000, roughly 46.5 percent of it came from staunchly Democratic Lucas County, dominated by Toledo, the second-most unionized city in the nation.
When Lucas County results are removed from northwestern Ohio’s vote totals in the past 10 presidential elections, Republican candidates received 16 percent more of the vote. Lucas County supported the Democrat by an average of 54 percent in those elections. Bush carried Wood County, the region’s second-largest, by nine points over Al Gore in 2000, but Democrat Bill Clinton won it in 1992 and 1996.
Sandra Barber, Fulton County’s recorder and two-decade chairwoman of the county GOP, said the farm counties around Toledo are imbued with a conservative German ethic that values hard work, self-reliance and Christian beliefs. Perhaps no community in northwestern Ohio personifies the area’s Republicanism more than Archbold, a prosperous Fulton County village with more jobs than residents. Fifty miles to the east, there is a different political universe in Toledo, where support for Bush is as barren as the moon’s surface.In 2004, Ottawa County extended its perfect record to 11 straight presidential elections as the county went to Bush.
posted by jr on Mar 04, 2008 at 06:12:37 pm #