ALEXANDRIA, a city of Virginia, in N. America, capital of the county of the same name, and lately in the district of Columbia. It is beautifully situated on the right bank of the river Potomac, six miles south of Washington. It is neat and well-built, has a good harbour, and a considerable trade in flour. The Chesapeake and Ohio Canal begins here, which must tend to increase the prosperity of the town. In 1850 the population amounted to 8795; and that of the county to 10,216.