After graduation from Yale, he began working in the lumber business, like his father and grandfather, eventually becoming president of Sage Land and Development Company, as well as a director of several banks and insurance companies in Albany.
 The family later donated the funds to build Sage Hall at Yale, at the time, the largest forestry school on the continent.

Sage was a Republican member of the New York State Assembly (Albany Co., 4th D.) in 122nd New York State Legislature, serving from January 1 until December 31, 1899.

Later from January 1, 1911 until December 31, 1920, Sage was a member of the New York State Senate, sitting in the 134th, 135th, 136th, 137th, 138th, 139th, 140th, 141st (all eight 28th D.), 142nd and 143rd New York State Legislatures (both 30th D.).
 While in the State Senate, he served as Chairman of the Finance Committee from 1914 to 1920.

Afterwards he was Chairman of the State Hospital Development Commission.
 He was a delegate to the 1916, 1920 and 1924 Republican National Conventions.

In 1932, he wrote to The New York Times about New York's finances and warning against increasing taxes.
After graduation from Yale, he began working in the lumber business, like his father and grandfather, eventually becoming president of Sage Land and Development Company, as well as a director of several banks and insurance companies in Albany.  The family later donated the funds to build Sage Hall at Yale, at the time, the largest forestry school on the continent.
Sage was a Republican member of the New York State Assembly (Albany Co., 4th D.) in 122nd New York State Legislature, serving from January 1 until December 31, 1899.
Later from January 1, 1911 until December 31, 1920, Sage was a member of the New York State Senate, sitting in the 134th, 135th, 136th, 137th, 138th, 139th, 140th, 141st (all eight 28th D.), 142nd and 143rd New York State Legislatures (both 30th D.).  While in the State Senate, he served as Chairman of the Finance Committee from 1914 to 1920.
Afterwards he was Chairman of the State Hospital Development Commission.  He was a delegate to the 1916, 1920 and 1924 Republican National Conventions.
In 1932, he wrote to The New York Times about New York's finances and warning against increasing taxes.
Henry M. Sage