Before the District of Columbia Organic Act of 1871, the District of Columbia had separate local municipalities, including Georgetown and the City of Washington (i.e., Old City below what is now Florida Ave.). Outside of those two, there was also the more rural area known as Washington County.
The Organic Act united all three into the District of Columbia, which had a single territorial government, headed up by a Governor. That only lasted from 1871 to 1874.
Between 1820 and 1871, the City of Washington had 17 popularly elected mayors, and the last one was Matthew Gault Emery, a Republican.
Matthew G. Emery
Emery was originally from New Hampshire, having been born there in 1818. He spent his early adulthood in Baltimore as an apprentice architect and builder, and after a few years moved to Washington in the hopes of gaining contracts to work on government buildings.
Matthew Emery in the 1871 city directory
His involvement in building notable structures in the city is full of interesting trivia, including the fact that he cut and laid stones for the Department of Treasury’s building, the U.S. Patent Office, the White House, and the his most notable achievement, cutting and laying the cornerstone for the Washington Monument in 1848. After the stalled project was restarted, a full 36 years later, he was invited back to see the capstone be placed on top of the Monument.
He lived for a time at 621 F St. NW in a very full home, which included his wife Mary, children Mary, Clara, Matthew Jr., Julia, and Mary, plus a cook, nurse, servant, and coachman.
Emery family in the 1870 U.S. Census
Emery was not mayor for long, having a term of just 11 months, but during his time in office, he oversaw the beginning of the largest construction projects in Washington, up to that time, including grading and paving 132 streets and building a seawall along the Anacostia River.