Leroy Sunderland Buffington was born in Cincinnati, Ohio, in 1847 and received all of his formal education there. His first employment was with the architectural firm of Hannaford and Anderson, whom he left in 1871 to move with his wife of two years to St. Paul. He entered partnership with Abraham Radcliffe, an established architect, which lasted until 1874 when he moved to Minneapolis and opened an office that he continued to maintain until 1931. He had no partners.

In 1880, he was appointed the official architect of the St. Paul, Minneapolis and Manitoba Railway Company, and by 1885 he had one of the largest practices in the Twin Cities. Near the end of his life, he credited himself with designing $20 million' worth of structures throughout the United States. He applied for and received a patent in 1887 for the steel skeleton method of construction for high-rise buildings, the basis upon which all modern skyscrapers are built. However, his claim was challenged in a court suit which he eventually lost.

Buffington died in Minneapolis in 1931.