Montgomery Blair, 1813-1883, was a lawyer and postmaster general in President Lincoln's cabinet.

Blair was born May 10, 1813 as the eldest son of Francis Preston Blair, Sr., and was reared in Franklin County, Kentucky. He graduated from the U.S. Military Academy, West Point, New York in 1835, served in Seminole War, then resigned his commission to study law at Transylvania University in 1836. In 1837, Blair settled in St. Louis as the protege of politician Thomas Hart Benton. There he served as mayor of St. Louis, 1842-1843; delegate to Democratic National Convention, 1844, 1848, 1852; and judge of Court of Common Pleas, St. Louis, 1845-1849. In 1849, he resigned to resume law practice, and in 1853 moved to Maryland and practiced chiefly before the U.S. Supreme Court. Blair was appointed the first solicitor-general for U.S. Court of Claims, 1855, then was dismissed by James Buchanan because of his pronounced views on slavery. Blair presided at the Maryland state Republican convention and was delegate to the National Convention at Chicago in 1860. From 1861-1864, he served as postmaster general in President Abraham Lincoln's cabinet. He supported the Democratic party in 1868, 1872, and 1876. In 1876, to support Democratic nominee Samuel J. Tilden, Blair established the newspaper, The Union (Washington, D.C.). He was elected to the Maryland House of Delegates in 1878, and ran unsuccessfully for Congress in 1882.

Blair's first marriage was to Miss Buckner of Virginia, d. 1844; his second to Mary E. Woodbury, daughter of Judge Levi Woodbury of New Hampshire. Blair died in Silver Spring, Maryland on July 27, 1883.