In 2009, Virginia voters angry over the ongoing economic recession and President Obama’s push for health-care reform elected Republican Robert F. McDonnell by a 17-point margin. Four years later, despite Obama’s still-low approval ratings, Virginia chose Democrat Terry McAuliffe.

When Terry McAuliffe was elected governor of Virginia Tuesday night, it was the latest indication the state might slightly favor Democrats. (The Washington Post)

Exit polls showed the Virginia electorate has changed substantially over the last four years. And that made the difference in last Tuesday’s election: If the 2013 electorate had looked the same as the 2009 electorate, the results would have been different, and Republican Ken Cuccinelli would be Virginia’s governor in waiting.

Democrats credit an aggressive field program, bolstered by new technological innovations using Facebook and some old tactics lifted from Obama’s team in 2012, with a surge in younger and African American voters — the overwhelmingly Democratic contingents that helped McAuliffe win a narrow three-point victory.