In 1695, the land that now encompasses Montgomery, Prince George's and Frederick counties, as well as Washington, D.C., was designated as Prince George's County. The area was divided in 1748 and the western portion - including the land that would ultimately be Montgomery - became Frederick County. On August 31, 1776, Dr. Thomas Sprigg Wootton, a member of the Maryland Constitutional Convention, introduced a bill to divide Frederick into three counties - Frederick, Montgomery and Washington. The bill passed on September 6, 1776. These were the first counties in America to be established by elected representatives. The names selected for the new counties also broke with tradition. Earlier counties had all been named for old world figures such as Prince George and Queen Anne, but these were named after two popular Americans of the time - George Washington and Richard Montgomery.

Richard Montgomery was born on December 2, 1738 in Raphoe, Ireland. At 18 he was commissioned as an officer in the British army and fought in the French and Indian Wars, before emigrating to America in 1772. He was commissioned a brigadier general in the fledgling colonial army and he commanded an expeditionary force sent to Canada that captured Montreal. On December 4, 1775 his forces laid siege to Quebec. Although his troops were greatly outnumbered, he led several daring attacks on the fortress. On December 31, he was killed by cannon fire.