He was the fifth mayor of Oshkosh, and served one year each in the Wisconsin Senate (1862) and State Assembly (1858) representing Winnebago County.

At age 15, his father paid for him to attend Allegheny College, but Hay declined and instead chose to pursue an apprenticeship in tin, copper, and iron working.

He first visited the area that would become Oshkosh, Wisconsin, in 1846, when he accompanied a friend on a trip to the trading post which then existed at that location.

[1] In the Fall of 1848, he felt he had sufficient resources to start off on his own and came to the site of Oshkosh, which at the time had about 100 inhabitants, mostly of French and Indian heritage.

[1][2] Throughout most of his time in banking, Hay was a close associate of Philetus Sawyer, who served as mayor, congressman, and United States senator.

[5] At the time, his district comprised all of the city of Oshkosh and a few surrounding towns in the central part of Winnebago County.

[1][7] In the midst of the first year of the American Civil War, Winnebago County's incumbent state senator Horace O. Crane, resigned from office to become a surgeon in the Union Army.

Samuel Hay was the Republican nominee for the special election to fill the remaining year of Crane's term.

In 1876, he was appointed to the board of regents of the State Normal Schools by Governor Harrison Ludington, serving until February 1879.

[2] He was survived by only two of his children, his eldest son, Samuel Thayer Hay died of disease eight months before his father.

[10] His only known daughter, Mary, married Frank Merrill Caldwell, a career U.S. Army officer who served as a brigadier general in World War I.

[12] Hay, his wife, and all of their children, as well as General Caldwell, are interred at the family's massive mausoleum in Oshkosh's historic Riverside Cemetery.