Montgomery County, officially the County of Montgomery, is a county in the U.S. state of Maryland. It is the most populous county in Maryland. The county seat and largest municipality is Rockville, although the census-designated place of Germantown is the most populous place. Most of the county’s residents live in unincorporated locales, of which the most built up are Silver Spring, and Bethesda, though the incorporated cities of Rockville and Gaithersburg are also large population centers as are many smaller but significant places.
As one of the most affluent counties in the United States, it also has the highest percentage (29.2%) of residents over 25 years of age who hold post-graduate degrees. In 2011, it was ranked by Forbes as the 10th richest in the United States, with a median household income of $92,213. Montgomery County, like other inner Washington, D.C. suburban counties, contains many major U.S. government offices, scientific research and learning centers, and business campuses, which provide a significant amount of revenue for the county.