[16][17][18] Much of the area remains rural, however the region saw suburban growth in the late 20th and early 21st centuries as Washington's suburbs expanded southward.

[13] The colony originally focused on tobacco farming and was very successful although disease was a problem and many settlers died until immunities built up in the population.

[30][31][32][25] St. Mary's City was abandoned as a capital but was slowly consolidated from smaller farms into a large, single slave plantation by the late 1600s.

[14] From the late 1600s to early 1700s, about half of Maryland's enslaved population lived in Calvert, St Mary's, Prince George's, and Charles counties.

[14] The profits from slavery also provided the means for Maryland's gentry to gain power and dominate politics.

[35] A notable abolitionist from southern Maryland was Josiah Henson, a slave who was born in Charles County before escaping to Canada.

Henson wrote an autobiography that inspired Harriet Beecher Stowe's novel, Uncle Tom's Cabin.

[14] During the American Revolutionary War, British forces landed on St. George Island in St. Mary's County on July 15, 1776, under the command of John Murray, 4th Earl of Dunmore.

[17][37] Dunmore's forces were defeated by local Flying Camp militia led by Captain Rezin Beall, and they left the island on August 9, 1776.

By nightfall on August 24, 1814, British forces entered Washington and burned several government buildings.

[41] Similarly to what occurred in the Revolutionary War, enslaved Marylanders fled to British controlled areas to receive freedom.

From the war's beginning, however, large numbers of Union occupying troops and patrolling river gunboats prevented the state's secession, although frequent nighttime smuggling across the Potomac River with Virginia took place, including of Maryland men volunteering for Confederate service.

John Wilkes Booth was helped by several people in his escape through the area and in crossing the river after killing President Abraham Lincoln.

[16][42] Thousands of captured Confederate troops were confined in harsh conditions at Point Lookout Prison Camp at the southern tip of the peninsula.

[14] Southern Maryland was traditionally a rural, agricultural, oyster fishing and crabbing region; linked by passenger and freight steamboat routes.

(The latter highway was named after Robert Crain, an attorney who owned the state's largest farm, Mount Victoria, and who campaigned for the road's construction[45]).

[47] Poverty was common in St. Mary's County in the 1960s,[48] and gambling in the region came to be seen as a blight and was outlawed by Governor J. Millard Tawes and the state legislature.

Other smaller industries include a nuclear power plant[59] and a liquified natural gas terminal[60] (both in Lusby), a Naval ordnance test ground (at Indian Head),[61][62] electric power plants (at Aquasco and Morgantown)[63] and an oil terminal[64] (at Piney Point).

[93] Oysters are still widely available although they were once fished from the bay and its tidal tributaries in greater numbers, and are served either fried, raw, or stuffed.