Captain John Smith was the first European to explore the river, noting it on his 1612 map as the Bolus River. The "Red river", named after the clay color, is considered the "old Bolus", as other branches were also labeled Bolus on maps. The origin of the indigenous-derived modern name is unclear. The name first appears in land records from the 1650s, and is additionally labeled in a map of
George Alsop created in 1660. Modern etymological research suggests that the name originates from
Algonquian-speaking peoples as "pota-psk-ut", meaning "at the jutting ledge of rock" or "at the rocky point or corner." This was thus a reference to a location near the river, which settlers adapted for the river itself. This location is surmised to be the White Rocks, an outcropping of rocks opposite to where Rock Creek feeds into the Patapsco at Pasadena. As the river was not navigable beyond Elkridge, it was not a significant path of commerce; in 1723, only one ship was listed as serving the northern branch, and four others operating around the mouth. The first land record regarding Parr's Springs, the source of the South Branch, dates from 1744, when John Parr laid out a tract he called Parr's Range. During the Civil War, Parr's Spring was a stop for the
Army of the Potomac's
Brig. Gen. David M. Gregg's cavalry, on 29 June 1863, while en route to
Gettysburg, Pennsylvania. Parr's Spring was dug to form a pond in the 1950s, filled by seven spring heads that form the headwaters of the South Branch of the Patapsco River. Beginning in the 1770s, the Patapsco River became the center of Maryland industrialization. Milling and manufacturing operations abounded along the river throughout the eighteenth and nineteenth centuries, generally powered by small dams. The
Baltimore and Ohio Railroad's
original main line was constructed in 1829 west along the Patapsco Valley; the nation's first railroad, the route remains, though much altered. Many railroad bridges were built in the valley, including the
Thomas Viaduct, which is still in use, and the
Patterson Viaduct, now in ruins. The 1907
hydropower Bloede's Dam powered flour mills. An 1868 flood washed away 14 houses and killed 39 people around
Ellicott City. A 1923 flood topped bridges. In 1952, an wall of water swept the shops of Ellicott City. A 1956 flood severely damaged the
Bartigis Brothers plant. In 1972, rainfall from the remnants of
Hurricane Agnes damaged Ellicott City and the Old Main Line. Two died in the July
2016 Maryland flood that ravaged Main Street in Ellicott City, followed two years later by a May
2018 Maryland flood that took the life of a rescuer. The mouth of the Patapsco River forms Baltimore Harbor, the site of the
Battle of Baltimore during the
War of 1812. This is where
Francis Scott Key, aboard the British , wrote "
The Star-Spangled Banner", a poem later set to music as the national anthem of the United States. Today, a red, white, and blue buoy marks where the ship was anchored.
Bloede's Dam, a hydroelectric dam built in 1906, was on the Patapsco River within
Patapsco Valley State Park, a nearly complete barrier to
anadromous fish passage. Although a fish ladder was installed in 1992, it blocked five of six native fish species trying to run upstream to spawn. Efforts to remove Bloede's Dam began in the 1980s when nine drowning deaths occurred, and also to restore fish passage to a large portion of the Patapsco River watershed. Dam demolition began on 12 September 2018, opening the fishery and creating a rocky rapid for kayaking. Two dams upstream of Bloede's Dam, Simkins and Union, were removed in 2010. The removal of Bloede's Dam leaves Daniels Dam, upstream, as the last remaining dam along the mainstem Patapsco River. ==Course==