Humphreys was born in Haverford, Pennsylvania and died in the same place.
As a youth Humphreys was apprenticed to a shipbuilder in Philadelphia, Pennsylvania. During the American Revolutionary War he was active as a designer, and played a major part in planning Randolph, a frigate, and a 74-gun ship which was never built. After the war Humphreys became an important shipbuilder in Philadelphia; and, when Congress in 1794 passed the act providing for the construction of six frigates, he was called upon to design them. He was appointed Naval Constructor 28 June 1794 and began work on these important ships, the beginnings of the U.S. Navy.
United States was built by Humphreys in Philadelphia, and was the first of the new ships to be launched on 10 May 1797. These brilliantly designed and skillfully handled vessels, larger and faster than other ships of their class, formed the core of the Navy during the War of 1812, and scored several stirring victories against powerful British ships. Humphreys' genius is evident by the fact that one of these ships, Constitution (Old Ironsides), is still afloat as of 2005.
His brother was Charles Humphreys, a member of the Continental Congress. His son was another noted naval architect, Samuel Humphreys. His grandson, General Andrew Atkinson Humpreys, served with great distinction throughout the American Civil War. Joshua, Samuel and Andrew are buried at the Congressional Cemetery in Washington, D.C.
Joshua was apprenticed at an early age to a ship carpenter in Philadelphia.
Humphreys, who replied: "I do not know that I possess the merits attributed to me, but, be they great or small, I owe them all to the flag of my country."--Samuel's son, Andrew Atkinson, soldier, born in Philadelphia, Pennsylvania, 2 November, 1810; died in Washington, D. C., 27 December, 1888.
General Humphreys was elected a member of the American philosophical society in 1857, a member of the American academy of arts and sciences in 1863, and was one of the incorporating members of the National academy of sciences in the last-named year.