John Wellborn Root (January 10, 1850 – January 15, 1891) was a significant American architect who worked out of Chicago with Daniel Burnham. He was one of the founders of the Chicago school style. Root was born son of Sidney Root in Lumpkin, Georgia, and raised in Atlanta. When Atlanta fell during the American Civil War, he fled to Liverpool, England; it is said his later work was influenced by the work of Liverpool Architect Peter Ellis. While there he studied at Clare Mount School. He returned to the U.S. and received a degree from New York University in 1869. After he graduated, Root took a job with James Renwick, Jr. of Renwick and Sands of New York as an unpaid apprentice. Later he took a job with J.B. Snook in New York. While working for John Butler Snook, he was a construction supervisor on New York City's Grand Central Station. He and Daniel Burnham formed the firm of Burnham and Root and worked together for 18 years. During an economic downturn in 1873, he earned extra income by hiring himself out to other firms and as the organist at the First Presbyterian Church.
He developed the floating raft system of interlaced steel beams to form the foundation of tall buildings that would not sink in Chicago's marshy soil. Root's first use of this revolutionary system was for the Montauk building in 1882. He later transferred this steel frame to the vertical load bearing walls in the Phenix building of 1887, in imitation of William LeBaron Jenney's Home Insurance Building of 1885.
Root, Burnham, Dankmar Adler, and Louis Sullivan formed the Western Association of Architects because they felt slighted by East Coast architects. Root served as president in 1886. In 1887, he was elected a director of the national American Institute of Architects.
He worked on the plan for the World's Columbian Exposition, but before it was constructed Root died from pneumonia in 1891 at the age of 41. Along with many other famous Chicago architects, his final resting spot is in Uptown's Graceland Cemetery.
Root married Mary Louise Walker in 1879 but she died six weeks later. He married again in 1882 to Dora Louise Monroe. Their son John Wellborn Root, Jr. was also a Chicago architect.