| Jefferson Marion Long Jr. | |
| Birth Date: | 5 March 1927 |
| Birth Place: | Loris, South Carolina, U.S. |
| Office: | Member of the South Carolina Senate |
| Term Start: | 1985 |
| Term End: | 1990 |
| Party: | Democratic |
| Alma Mater: | University of South Carolina |
Jefferson Marion Long Jr. (March 5, 1927 – April 25, 2003), also known as J. M. Long Jr., was an American politician. He served as a Democratic member of the South Carolina Senate.
Long was born in Loris, South Carolina. He attended the University of South Carolina.
Long served in the South Carolina Senate from 1985 to 1990. He lost his seat as a result of Operation Lost Trust, after pleading guilty to accepting a $42,000 bribe.
Long died[1] on April 25, 2003, at the age of 76.