Erasmus T. Carr FAIA (October 25, 1825 – May 12, 1915) was an American architect in practice in Leavenworth, Kansas, Denver, Colorado and Miles City, Montana from 1857 until his retirement in 1898.

This was planned as a permanent move, but in the spring of 1857 he returned to Leavenworth, where he opened an architect's office.

While maintaining his independent practice, he was again hired by the government in 1859 to take charge of construction at Fort Leavenworth.

During the Civil War Carr intended to enlist, but did not at the request of General Jesse L. Reno, who thought he was most useful at Leavenworth.

This was dissolved in 1893 and Carr moved on to Miles City, Montana, where his daughter and son-in-law, Jepp Ryan, lived.

In 1898 Carr retired from practice and Ryan closed out his business interests in Miles City.