A curious historical note: Elmslie claimed to have been born in 1871, and he carefully kept his true birth year a secret all his life except from a very few people. The apparent reason for this was due to his immigration status in 1885, when he joined his father John Elmslie in Chicago from his native Scotland. Had Elmslie divulged his true age, he would have been ineligible to enter the United States as a dependent family member. Elmslie died on April 23, 1952 and is interred at Graceland Cemetery in Chicago.

Elmslie began his apprenticeship in the office of William LeBaron Jenney, who originated the steel frame skeleton used in modern building construction. In 1887, Elmslie joined Frank Lloyd Wright and George Maher in the office of Joseph Lyman Silsbee, a Western New York based architect who had moved to Chicago. After Wright left to go to work for Dankmar Adler and Louis Sullivan in 1887, he recommended Elmslie to Sullivan. In 1888, Elsmlie joined Wright at Adler & Sullivan, which led to a 20-year association between Elmslie and Sullivan. Wright and Elmslie shared an office next to Sullivan’s. Elmslie was Sullivan’s chief draftsman and ornamental designer. He detailed the ornamentation for Sullivan’s Wainwright Building in St. Louis, the Schlesinger & Mayer Department store in Chicago and the National Farmers Bank in Owatonna, Minnesota.

The architectural practice most widely known as Purcell & Elmslie consisted of three partnerships. The first, Purcell & Feick, was created at Minneapolis, Minnesota, in 1907 between Purcell and his Cornell School of Architecture classmate, George Feick, Jr. George Elmslie and Purcell had been friends since 1903, when Purcell worked for a short while in the office of Louis Sullivan, and Elmslie was an informal influence in the work of Purcell & Feick. In 1909, Elmslie joined the office in Minneapolis, Minnesota, and the name of the firm changed to Purcell, Feick, & Elmslie in 1910. Feick left the partnership in 1912, and the name of the practice became Purcell & Elmslie until being dissolved in 1921.

Elmslie was elected a Fellow in the American Institute of Architects in 1947.