COLUMBUS, Ohio (AP) -- 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.
Given the storied history and high stakes, it's easy to see why Ohio, in primaries and general elections alike, always seems to host races that are hard-fought, if not determinative.
This year is shaping up as more of the same.
"You're going to grow probably weary of seeing me in Ohio," likely GOP nominee John McCain told voters last week as he campaigned throughout the state. He mentioned at every turn that no Republican has ever won the White House without winning Ohio.
Not to be outdone, Barack Obama and Hillary Rodham Clinton - Democrats competing for the chance to face the Arizona senator - repeatedly played to Ohio's pride of having chosen the eventual president in every election starting in 1964.
Republicans, Democrats and independent analysts expect a neck-and-neck contest again for the state's 20 electoral votes in November. Ohio tipped the election to President Bush four years ago, and could be poised for another high-profile role.
A recent Ohio Poll by the University of Cincinnati's Institute for Policy Research showed that no matter which Democrat wins Tuesday's hotly contested primary, the general election race will be tight. Each Democrat is in a virtual tie with McCain in hypothetical head-to-head matchups.
So, what, exactly, makes Ohio so closely divided politically and such a strong barometer of the country's pulse?
The answer starts with the state's birth as part of the Northwest Territory in 1803. Liberal-leaning New Englanders traveled west to settle Northern Ohio while conservative-tilting Virginians moved up to inhabit Southern Ohio.
Over the years, unions established a major presence across the state's industrial north as steel mills, tire factories and other blue-collar jobs flourished along Lake Erie. Small businesses and agriculture were the norm in the south and elsewhere.
Today, there's a Republican stronghold in the southwest, a Democratic bastion in the northeast and swing-voting regions everywhere else that, like the nation, vacillate between electing Republicans and Democrats to the White House based on their satisfaction or dissatisfaction with the status quo.
Ohio tends to pick by the narrowest of margins. The winner of the most recent presidential elections won by less than 6 percentage points. Democrat Bill Clinton prevailed in 1992 and 1996; Bush, in 2000 and 2004.
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.
"Politically, Ohio has a very good mix of people from both the extremes and many who are in the middle when it comes to the issues facing the country," said Eric Rademacher, co-director of the Ohio Poll. "There is a great deal of socio-economic diversity in Ohio that's representative of the nation, and there's also an ideological diversity in Ohio that does a good job of representing the politics of the remaining 49 states."
Two years ago, Ohio's independents, who long have leaned right, shifted to the left to help Democrats sweep scandal-plagued Republicans out of the governor's mansion and other statewide offices.
This fall's election will indicate whether that shift was lasting or a fluke in a state whose political leanings tend to go in cycles.
For example, a pair of two-time Bush voters turned up at a Clinton event last week in Zanesville and said they are considering voting for a Democrat because they are angry about where the country is headed with a Republican at the helm.
"For the first time in my life, I'm leaning toward the Democrats," said Debbie Kirsch of New Concord, 47, a Republican-voting independent. "I've been so frustrated this year. I don't feel that any of them are in tune with what I want - jobs and health care, someone who is going to focus on those issues that affect my everyday life."
"I want better for my kids," added Kirsch, a welfare-to-work adviser who has a second job teaching English at night. It's a two-job lifestyle that she has seen repeated among three of her adult children; a fourth goes to school full time and also works full-time.
Next to her, Georgeanna Meighen of Pleasant City echoed Kirsch's sentiments. She expressed deep disappointment about the past eight years: "Nothing has gotten better."
Meighen, a 42-year-old working toward a degree at a state technical college, said she, too, is not yet sold on any of the candidates.
"I want to really look at what everybody is saying, the values and beliefs they have to see if they are the same as mine," she said. "I want someone to fight for us."