Loudoun one of the fastest growing counties in America
In the last year the population in Loudoun has grown by more than 12,000 people, according to the Census' Population Estimates data.
That's almost 4 percent of the population, making it the 17th largest jump in population of any county in America.
The county grew from 337,248 people to 349,679 during the one-year period from July 1, 2012 to the same date in 2013.
Loudoun is also the second fastest-growing county in the country with a population of more than 250,000 people.