After the Panic of 1837 and the decline of canal traffic following construction of railroads across the state, her father's businesses and warehouses began to fail.

[citation needed] Olivia Slocum supported herself by teaching for 20 years in Syracuse, New York, where she lived with her parents, and in Philadelphia.

[1]: 163–164 In 1905, Olivia Sage told Syracuse University that she would purchase Yates Castle and its surrounding property to house a teachers' college.

[citation needed] In 1915, Mrs. Russell Sage (as she is referred to in records) purchased the National Training School in Durham, North Carolina from Thomas A. Gorman.

The institution, which is now known as North Carolina Central University, had originally belonged to Dr. James E. Shepard, who lost ownership due to debt.

[citation needed] Two years later, Sage gave $300,000 to Cornell University for the construction of a women's dormitory, Risley Hall, named after her mother-in-law.

[citation needed] In 1912, Sage acquired Marsh Island in the Gulf of Mexico, dedicating it as a refuge for birds and other wildlife.

[8][9] Olivia Slocum Sage regularly spent her summers at a house in Sag Harbor, New York, a former whaling and fishing village on eastern Long Island.

[citation needed] Olivia Sage's summer residence for many years in the village was later adapted for use as the town's Sag Harbor Whaling Museum.

In 2017, in honor of the 100th anniversary of women receiving the right to vote in New York State, the William G. Pomeroy Foundation gained approval for installation of a historic roadside marker outside Sage's former Sag Harbor home to acknowledge her contributions to the suffragist movement.

[10] The historian Ruth Crocker has studied how Sage provided in her will for distribution of more wealth: her legacy had fifty-two equal parts.

In addition she gave extensively to the Rensselaer Polytechnic Institute (RPI) and the Emma Willard School, both in Troy.