John Wellborn Root (January 10, 1850 - January 15, 1891) was a significant U.S. architect who worked out of Chicago with Daniel Burnham. He was one of the founders of the Chicago school style. Root was born in Lumpkin, Georgia, and raised in Atlanta. When Atlanta fell during the American Civil War, he fled to the Liverpool in the United Kingdom, it 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. 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 marshy soil 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. He worked on the plan for the World Columbian Exposition but died before it was constructed.

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.

Root married Mary Louise Walker in 1879 but she died six weeks later. He married again in 1882 to Dora Louise Monroe. His son John Wellborn Root, Jr. was also a Chicago architect.

Significant buildings

• Grannis Block (1880)
• Montauk block
• Rookery Building (1885)
• Phenix Building (1887)
• Monadnock Building , (1889)
• Reliance Building (1889), ground floor only -featured large display windows which set a new standard