In 2010, its population was 287,085. Its county seat is Ellicott City. The center of population of Maryland is located on the county line between Howard County and Anne Arundel County, in the unincorporated town of Jessup.
Due to the proximity of Howard County's population centers to Baltimore, the county has traditionally been considered a part of the Baltimore Metropolitan Area. Recent development in the south of the county has led to some realignment towards the Washington, D.C. media and employment markets. The county is also home to Columbia, a major planned community of 100,000 founded by developer James Rouse in 1967.
Howard County is frequently cited for its affluence, quality of life, and excellent schools. For 2011, it was ranked the third wealthiest county by median household income in the United States by the U.S. Census Bureau. Many of the most affluent communities in the Baltimore-Washington Metropolitan Area, such as Clarksville, Dayton, Glenelg, Glenwood and West Friendship, are located along the Route 32 corridor in Howard County. The main population center of Columbia/Ellicott City was named 2nd among Money magazine's 2010 survey of "America's Best Places to Live." Howard County's schools frequently rank first in Maryland as measured by standardized test scores and graduation rates.
To honor John Eager Howard, an officer in the American Revolutionary War and later the fifth Governor of Maryland, the area was designated the Howard District when Anne Arundel County was divided in 1839. The Howard District had the same status as a county except that it was not separately represented in the Maryland General Assembly. In 1851, the district became Howard County.
The county has a number of properties on the National Register of Historic Places.