| John A. McMahon | |
| State: | Ohio |
| Constituency: | 4th district (1875–1879) 3rd district (1879–1881) |
| Term Start: | March 4, 1875 |
| Term End: | March 3, 1881 |
| Preceded: | Lewis B. Gunckel |
| Succeeded: | Henry Lee Morey |
| Order3: | 7th |
| Office3: | Ohio State Bar Association |
| Title3: | President |
| Term Start3: | December 29, 1886 |
| Term End3: | December 28, 1887 |
| Preceded3: | William J. Gilmore |
| Succeeded3: | E. P. Green |
| Party: | Democratic |
| Birth Date: | 19 February 1833 |
| Birth Place: | Frederick County, Maryland |
| Death Place: | Dayton, Ohio |
| Restingplace: | Woodland Cemetery |
| Spouse: | Mollie R. Sprigg |
| Children: | two |
| Alma Mater: | Xavier |
John A. McMahon (February 19, 1833 - March 8, 1923) was a three-term United States Representative from Ohio from 1875 to 1881. He was the nephew of Clement Vallandigham, another Representative from Ohio.
McMahon was born in Frederick County, Maryland, and graduated from St. Xavier College in 1849. He taught at Xavier for a year, and settled in Dayton, Ohio, in 1852.[1] He studied law with his uncle, Vallandigham, and was admitted to the bar in 1854, forming a partnership with his uncle.[2] In 1861 he formed a partnership with George W. Houk, which lasted 19 years.[2]
He was elected to the Forty-fourth, Forty-fifth, and Forty-sixth United States Congresses, from 1875 until 1881.
McMahon was appointed by the House of Representatives as a manager to conduct impeachment proceedings against Secretary of War William W. Belknap.
He was unsuccessful for re-election in 1880.
He returned to private law practice in Dayton. He served as the president of the Ohio State Bar Association in 1886,[3] and was a losing candidate for the Senate in 1889.
He died in Dayton and was buried in Woodland Cemetery.
McMahon was married January 23, 1861, to Mollie R. Sprigg, of Cumberland, Maryland.[1] They had a son, J. Sprigg McMahon, and daughter, Louise McMahon.[4]