| Birth Date: | 9 March 1853 |
| Birth Place: | Valley Hill, Mississippi |
| Death Place: | Valley Hill, Mississippi |
| State Senate: | Mississippi State |
| Termstart: | January 1916 |
| Termend: | January 1920 |
| State House1: | Mississippi |
| District1: | Carroll County |
| District: | 26th |
| Termstart1: | January 1912 |
| Termend1: | January 1916 |
| Termstart2: | 1897 |
| Termend2: | January 1904 |
| Predecessor2: | W. F. Stevens |
| Party: | Democratic |
| Children: | 4 |
Lewis Simpson "Sim" Hemphill (March 9, 1853 - March 10, 1924) was an American politician and farmer. A Democrat, he served in both houses of the Mississippi Legislature in the late 19th and early 20th centuries.
Lewis Simpson Hemphill was born on March 9, 1853, in Valley Hill, Mississippi.[1] [2] [3] He was the son of James Simpson Hemphill and his wife, Anne Eliza (Mabry) Hemphill. He attended the public schools of his native Carroll County, Mississippi, and then became a farmer.
Hemphill was selected as the Chairman of the executive committee of Carroll County in 1892, and held that position for several years. In 1896, Hemphill was elected to fill in an unexpired term and represent Carroll County as a Democrat in the Mississippi House of Representatives, taking office in 1897. He was re-elected in 1899 to a full term and served from 1900 to 1904. He was again elected to the House in 1911 and served in the 1912–1916 term. In 1915, Hemphill was elected to represent the 26th District in the Mississippi State Senate for the 1916–1920 term.
Hemphill married Ida Julia Martin on December 16, 1885. They had four children, named Bessie, James Simpson, Everett Martin, and Vassar Dewey. Hemphill died on March 10, 1924, in Valley Hill.