He was also the president of the United States Chamber of Commerce during the early years of the Great Depression, in which capacity he supported the policies of Herbert Hoover and was a noted opponent of Franklin D. Roosevelt's New Deal.

Strawn relocated to Chicago, Illinois in September 1891, taking a position with Weigley, Buckley & Gray.

In 1913, Strawn was elected president of the Chicago Bar Association, and upon the outbreak of World War I, arranged for members of the association to take over without charge cases left unfinished by lawyers who volunteered to serve in the army.

During his time as president, he pushed for higher standards in legal education, including college study before admission to law school and a full three years of legal training before being eligible for admission to the bar.

As president of the United States Chamber of Commerce, in 1931, Strawn spoke out in favor of President Herbert Hoover's response to the Great Depression, arguing that it was up to business, not government, to solve the world's economic problems.

In 1934, as former president of the chamber, and a leader of its conservative wing, Strawn called on Roosevelt to "stop experimenting", stop encouraging Congress to pass "hysterical legislation", and return to a policy of balanced budgets.