The affluent and diverse suburbs of northern Virginia swung decisively toward Obama in 2008, providing most of his margin of victory in a state that hadn’t voted for a Democratic presidential candidate since 1964. Although Obama is not assured of another victory in the Commonwealth, Romney probably won’t win by rolling back Obama’s gains in the D.C. suburbs. Last cycle's consummate swing region is likely to again vote decisively for Obama in 2012, and Romney will need to look elsewhere for big gains in Virginia.

In 2000, Gore won the Virginia suburbs by just over 1 percentage point—better than the rest of Virginia, but not nearly enough to swing the state. Over the intervening eight years, the demographic composition of the region and the national Democratic coalition changed dramatically. According to the 2010 census, Prince William and Loudoun counties grew by 43 and 84 percent respectively, with minority groups representing a disproportionate share of new residents. Today, whites make up just 56 percent of residents in northern Virginia.

Simultaneously, Democrats made big gains among college-educated white voters. In affluent and educated metropolitan areas along the Atlantic and Pacific seaboards, Democrats consistently made gains in once Republican suburbs. These trends have been felt acutely in northern Virginia, perhaps the most educated region of the country, and an influx of northern moderates hastened Democratic advances. In Fairfax County, Democrats gained ground in every election since 1980, with Kerry becoming the first Democrat to win since LBJ.

In 2008, the region’s demographic changes—along with Obama’s big national gains among educated whites and minorities—produced a huge Democratic shift in northern Virginia. After voting for Kerry by 7 percentage points in 2004, Obama won Fairfax by 21 points in 2008. The two rapidly growing and increasingly diverse outer suburbs and exurbs swung even more dramatically. Prince William County voted for Bush by 7 points in 2004, but Obama won the new minority-majority county by 16 points in 2008. Altogether, Obama won northern Virginia by 22 points, providing statewide margin of victory. The rest of the state was a dead heat.

Although Bush was competitive in northern Virginia in 2004 and 2008, Romney will struggle to roll back Obama’s advances. National and state polls suggest that Obama’s “new coalition” of educated whites and minorities continues to offer 08’ levels of support to the President, and those voters represent an overwhelming share of the electorate in northern Virginia. So long as Romney struggles to make gains with educated whites, Northern Virginia won't be a swing region in 2012, and Romney will need to look elsewhere to make up ground.

By no means does Obama’s resilience in northern Virginia guarantee statewide victory in 2012. Northern Virginia only represented 27 percent of the electorate in 2008, and diminished African American turnout could combine with meaningful Romney gains elsewhere in the state to produce a GOP victory. In particular, Romney has opportunities in rural, white working-class areas in western Virginia and the less educated Tidewater region, including Virginia Beach and Norfolk. Obama did not perform particularly well in western Virginia, but national polls indicate that Obama is probably vulnerable to additional losses.

These facts appear to underlie the two campaigns' spending strategy. According to NBC's First Read, the Tidewater region (Norfolk/Portsmith media market) is the most heavily advertised area of the country, with western Virginia (Roanoke-Lynchburg media market) close behind. In contrast, the Obama campaign has not even aired advertisements in the expensive Washington media market, where the Obama campaign already appears well positioned and where plenty of dollars would be wasted appealing to the less politically significant residents of D.C. and Maryland.

Obama's resilient coalition of well educated whites and minorities is likely to translate into continued  strength in northern Virginia, one of the most diverse and educated regions of the country. Although both campaigns will attempt to maximize their share of the vote, northern Virginia should not be considered a swing area, at least if you interpret the term to imply that the region is likely to vote with the winner or that there are either a large number of swing voters. Romney will struggle to decisively move the needle in the D.C. suburbs. For Romney to win Virginia, as he very well might, he will find gains elsewhere in the state.