Mcdowell, Irvin was born on October 15, 1818 in Columbus, Ohio, United States. Son of Abram Irvin and Eliza Shelden (Lord) Mcdowell.
Graduate College de Troyes (France) United States Military Academy, 1838.
Commissioned First lieutenant United States Army, 1842. Aide-de-camp to General Wool during Mexican War, also in Army of Occupation, 1848, adjutant general. Brevetted captain, 1847.
Commissioned major, 1856. Brigadier general in command Army of Potomac, also Department of Northeastern Virginia, 1861, commanded 1st Battle of Bull Run. Commissioned major general United States Volunteers in command I Corps, Army of Potomac, 1862.
Commanded troops Army of Rappahannock, territorial department of Rappahannock, relieved of command after 2d Battle of Bull Run (where he lost again), held territorial command San Francisco, 1864. Commanded Department of East, 1868, Department of South, 1872. Commissioned major general United States Army, 1872.
Retired, 1882; park commissioner San Francisco, circa 1882-1885. Planned park improvements of Presido reservation, laid out roads overlooking Golden Gate Bridge.