The New England Emigrant Aid Company was a transportation company founded in Boston, Massachusetts by activist Eli Thayer in the wake of the Kansas–Nebraska Act, which allowed the population of Kansas Territory to choose whether slavery would be legal. The company's ultimate purpose was to transport anti-slavery immigrants into the Kansas Territory. The company believed that if enough anti-slavery immigrants settled en masse in the newly-opened territory, they would be able to shift the balance of political power in the territory, which in turn would lead to Kansas becoming a free state when it eventually joined the United States.

Eli Thayer was a Republican member of the United States House of Representatives from 1857 to 1861. He was born in Mendon, Massachusetts. He graduated from Worcester Academy in 1840, from Brown University in 1845, and in 1848 founded Oread Institute, a school for young women in Worcester, Massachusetts. He is buried at Hope Cemetery, Worcester.