WHERE THE ELECTION COULD BE WON OR LOST WHERE THE ELECTION COULD BE WON OR LOST SWING COUNTIES SWING COUNTIES The most closely contested county in each of a dozen battleground states is in the suburbs: State County Metro area Colo. Arapahoe Denver Fla. Orange Orlando Mich. Oakland Detroit Minn. Anoka Mpls.-St. Paul Mo. Jefferson St. Louis Nev. Clark Las Vegas N.H. Rockingham Boston Ohio Hamilton Cincinnati Ore. Clackamas Portland Pa. Westmoreland Pittsburgh Va. Caroline Richmond Wis. St. Croix Mpls.-St. Paul Source: Analysis by Thomas Sanchez, University of Utah, and Robert Lang, Metropolitan Institute at Virginia Tech WASHINGTON  The presidential contest between John McCain and Barack Obama this fall is likely to be settled in places such as Clackamas, Arapahoe and Geauga. Suburban counties including these — outside Portland, Denver and Cleveland, respectively — have become the hardest fought and most closely won battlegrounds of national elections. "Suburbs are where the battle line is drawn," says Robert Lang, co-director of the Metropolitan Institute at Virginia Tech. He says suburban voters tend to be "pragmatists and non-ideological, and they want problems fixed." BE A STRATEGIST: Build your general election scenario A generation ago, cities were considered predominantly Democratic and suburbs safely Republican, but the political leanings of suburbs shifted as they became more racially diverse and densely populated. Most Americans now live in suburbs. Lang and demographer Thomas Sanchez of the University of Utah analyzed presidential, gubernatorial and Senate elections since 2000 and identified the 94 most competitive counties in a dozen battleground states. Their study will be released next month. The closest contests were in "inner suburbs," those most closely tied to cities. The biggest swing from election to election was in "mature suburbs," communities that grew up in the mid- to late 20th century and are relatively stable in population. In Northern Virginia, for instance, Fairfax County moved into the Democratic column in the 2004 presidential election for the first time in 40 years. The next ring of faster-growing communities are called "emerging suburbs," and the farthest from cities are "exurbs." The denser the population, the more Democratic the vote. Still, even in Republican-leaning "exurbs" there has been significant movement between the two major parties. Democratic candidates increased their vote by nearly 9 percentage points in those more sparsely populated communities from 2002 to 2006, one reason for their gains in Congress and statehouses that year. The rise of suburbs as the nation's key battleground has affected what issues candidates emphasize — rising gas prices are particularly important to the many suburbanites who commute by car — and which states the candidates target. "Around Philadelphia, the movement away from solid Republican … in the so-called collar counties … means Pennsylvania has gotten to be very even, and likewise in Virginia," says McCain adviser Frank Donatelli, deputy chairman of the Republican National Convention. "It's put Virginia in play." Guidelines: You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. You share in the USA TODAY community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language decent. Use the "Report Abuse" button to make a difference. Read more