The District continues to attract newcomers at a greater pace than its neighbors.
The District of Columbia has grown by 13,000 residents in the past year, bringing the city's total population to more than 646,000.
The new figures released Monday are a Census Bureau estimate and represent growth of about 2 percent.
D.C. Mayor Vincent Gray says the additional 1,100 residents a month are evidence the city is booming, and more people are living in the nation's capital than at any time since the 1970s.
"The new population estimate demonstrates that the District continues to be one of the most attractive and competitive cities in the nation," said Mayor Gray. "I set a goal for this city to be healthiest, greenest, and most livable city in the country within 20 years. These results tell us that people across the nation and around the world already see us as well on our way.
An analysis of Census data last month found that the District was the most popular destination in country among Millenials, contributing to the 8,584 net new residents moving to the area.
Some of the growth also came au naturel, with a baby boom driving a natural increase (births minus deaths) of 4,438 residents between July 2012 and July 2013. Despite the fact that the District is one of the most expensive places in the country to raise a child, it's the sixth straight year the births in the District exceeded 9,000.
Nearby Maryland and Virginia also gained residents in the past year, though their gains are an increase of less than 1 percent. Maryland gained about 44,000 residents while Virginia added 74,000 residents.
Maryland now has more than 5.9 million people while Virginia has more than 8.25 million.