Frank St. John Sidway (December 15, 1869 – January 17, 1938), was a Buffalo, New York lawyer and National Guard leader.

[6][7] Spaulding supported the idea for the first U.S. currency not backed by gold or silver, thus helping to keep the Union economy afloat during the Civil War.

[9] March 1, 1894, he was commissioned as second lieutenant in the Seventy-fourth infantry regiment of the New York National Guard.

On December 15, 1898, also his 29th birthday, he was commissioned a captain of the 202nd New York Volunteer Infantry and set sail for Cuba as part of the Spanish–American War.

In the late 1930s, Sidway moved the now-NRHP listed Spaulding-Sidway Boathouse in Grand Island, New York about 270 feet northwest to his property in order to save the boathouse from demolition when the Spaulding estate was acquired in order to become Beaver Island State Park.