John Henninger Reagan was born to Timothy Richard Reagan (1797-1847) and Elizabeth Lusk (1799-1831) on 08 October 1818, in Sevier County, Tennessee. As a boy, he worked with his father at a tannery and on their small farm. He briefly attended nearby Nancy Academy until his mother died, when he took on the duties of caring for his four brothers and sister. After working a year for a local planter, he attended nearby Boyd's Creek Academy for fifteen months, then worked to support a year of study at Southwestern Seminary in Maryville, Blount County, Tennessee. In 1838, he left Tennessee for better opportunities.

     For a short time he managed a plantation near Natchez, Adams County, Mississippi, then headed to Texas and fought in the Cherokee War (1839). He subsequently worked as a deputy surveyor and frontier scout, and was elected a justice of the peace and captain of a militia company in Nacogdoches, Nacogdoches County, Texas. He married Martha Music on 19 April 1844, but she died the following year. He studied law, and in 1846 obtained temporary license to start his practice in Buffalo, Henderson County, Texas.

     Later that year, he was elected the first county judge of Henderson County and became a member of the Second Legislature of Texas. He formally passed the bar in 1848, and made an unsuccessful run for the state senate the next year. From 1852 to 1857, he served as Judge of the Ninth District of Texas and was a key member of the state's Democratic Party. On 23 December 1852, he married Edwina Moss Nelms (12 December 1832-21 July 1863). In 1857 he was elected a U.S. Representative from Texas, and was re-elected to the post in 1859.

     On 15 January 1861, Reagan resigned his seat in support of secession. He attended the Texas Secession Convention, was a deputy from his state to the Provisional Confederate Congress, and was appointed Postmaster General of the Confederacy on 06 March 1861.

     To help establish the Confederate Postal Service, he obtained samples of remaining Federal postal materials, on which to base new Confederate versions, and he also secured the services of several former Federal postal employees. For obvious financial reasons, the Permanent Confederate Constitution required that the Post Office Department become self sufficient by 01 March 1863. He achieved that goal by eliminating some routes and offices, increasing postal rates, and securing lower railroad shipping costs. Obtaining draft exemptions for postal employees helped ease personnel problems, but this often made him at odds with the War Department. Nevertheless, he garnered respect for his efficiency, and he also developed a close relationship with President Jefferson Davis (03 June 1808-06 December 1889).

     After the fall of Richmond, he accompanied Davis and the remaining Cabinet members in their flight. When George Alfred Trenholm (25 February 1807-09 December 1876) resigned, he was briefly charged with control of the Treasury. The group disbanded in Washington, Wilkes County, Georgia on 05 May 1865, and Reagan was captured with Davis on 10 May 1865 near Irwinville, Irwin County, Georgia. He was subsequently imprisoned with Vice-President Alexander Hamilton Stephens (11 February 1812-04 March 1883) at Fort Warren, in Boston Harbor.

     Following his release on 11 October 1865, he returned to his home in Palestine, Anderson County, Texas and rebuilt his farm. In 1866, he was married for the final time to Molly Ford Taylor (10 November 1847-). He was a member of the Texas Constitutional Convention in 1875, and was again elected to the U.S. House of Representatives. He served from 04 March 1875 to 04 March 1887, when he resigned to become U.S. Senator from Texas, serving 04 March 1887 to 10 June 1891. As a senator, he was instrumental in establishing the Interstate Commerce Commission. Upon returning to his home state, he was appointed a member of the Texas Railroad Commission and served as its Chairman from 1897 to 1903. He also made an unsuccessful run for the 1894 Democratic nomination for Governor.

     In his latter years, he was dedicated to the preservation of history and the memory of the Confederacy. In 1897, he helped found the Texas State Historical Association. He also regularly attended Confederate veterans meetings throughout the state. After his retirement in 1903, he worked for two years on completing his memoirs, which were published after his death on 06 March 1905. Reagan is buried in East Hill Cemetery in Palestine, Anderson County, Texas.