It’s like a quick fix for the electoral junkie who didn’t quite get enough the last go around. Every four years on the odd-numbered year after the presidential elections, Virginia and New Jersey hold elections for Governor (Virginia also elects its Lieutenant Governor and Attorney General as well). They are the only states to hold such elections at this time. These are called “off-off-year” elections because they occur two-cycles off the presidential election cycle (presidential election years being the “on” year elections, mid-term election years being the “off” year elections, and odd-year elections being the “off-off” year elections).
While odd election cycles might point to Machiavellian political games designed to enhance the electoral fortunes of one faction or another, the reason for Virginia’s unique place on the electoral calendar is really rather benign and has more to do with shifting populations, and arguments over proportional representation, and Virginia’s strong adherence to tradition than anything else.
After the census of 1840 was taken, it became apparent to everyone that the white population of the Western half of Virginia (the half that is now the state of West Virginia) far exceeded the white population of the rest of the state. Noting the disproportionate representation in the General Assembly favoring the 
Eastern half of Virginia, Westerners began calling for a constitutional convention to solve the problem, and the General Assembly soon complied. Delegates to the convention convened in Richmond in early October, 1850 and met for nearly a year.
In March 1851, while the constitutional convention was meeting, the Virginia General Assembly elected a new governor, as it had for the past 75 years for a three-year term. The newly elected governor Joseph Johnson was to take office on January 1, 1852, but in the ensuing months Virginia voters approved the new constitution which among other things expanded suffrage to all white male citizens 21 years or older who had been residents for at least two year and required the governor to be popularly elected to a four-year term. The constitution also prohibited the governor from serving successive terms, a prohibition that is still in place today.
