1. On August 20, 1794, a group of farmers in Maryland rebelled against the federal government's excise tax on whiskey. This event, known as the Whiskey Rebellion, was a protest against what was seen as an unfair tax on a staple of rural life.

2. On August 20, 1864, General Jubal Early's Confederate forces clashed with Union troops near Charles Town, West Virginia, just across the border from Maryland. This battle, known as the Battle of Summit Point, was part of Early's unsuccessful campaign to invade Maryland and threaten Washington, D.C.

3. On August 20, 1886, the first trolley car line in Maryland opened in Baltimore. The line, operated by the Baltimore Traction Company, ran from Mount Vernon Square to Hampden.

4. On August 20, 1959, the U.S. Navy launched the USS Skate, the first submarine to surface at the North Pole. The Skate was launched from the submarine base at New London, Connecticut, but was built at the Electric Boat Company's shipyard in Groton, Connecticut, which is just across the border from Maryland.

5. On August 20, 2010, the Chesapeake Bay Bridge-Tunnel celebrated its 47th anniversary. The bridge-tunnel, which connects the Eastern Shore of Virginia with the Virginia mainland, includes two tunnels, two bridges, and 17.6 miles of roadway. The Chesapeake Bay Bridge-Tunnel is often considered one of the engineering marvels of the modern world.