Baldwin was born in Staunton, Virginia. He graduated from Staunton Academy and then the University of Virginia in 1838. He was a member of the college's Board of Visitors from 1856–64. He married Susan Madison Peyton on July 4, 1852.
He was an earnest supporter of the Union during 1860, and worked for peace. He was elected to the state convention, as a Unionist, in 1861. He voted against the ordinance of secession, and was one of the members of the Union delegation that went to Washington, D.C. to interview President Abraham Lincoln. However, when secession of the commonwealth was ratified by the people of Virginia, he felt that it was his duty stay with his home state.
Baldwin was elected as a representative from Augusta County, to the First Confederate Congress, and was then reelected to the Second Confederate Congress (defeating incumbent Governor John Letcher) and served until the conclusion of the Civil War.
Following the war, Baldwin returned home. He was elected to the Virginia House of Delegates, under the new post-war United States government and was chosen as its Speaker. In this capacity, he showed exceptional ability and the rules of procedure which he evolved are still in use in Virginia, being known as "Baldwin's Rules."
Baldwin is buried in Thornrose Cemetery in Staunton, Virginia.
Jamerson, Bruce F., Clerk of the House of Delegates, supervising (2007). Speakers and Clerks of the Virginia House of Delegates, 1776-2007. Richmond, Virginia: Virginia House of Delegates.
|- style="text-align: center;"
|width="30%" align="center" rowspan="1"|Preceded by
Hugh W. Sheffey |width="40%" style="text-align: center;" rowspan="1"|Speaker of the Virginia House of Delegates
1865-1869 |width="30%" align="center" rowspan="1"| Succeeded by
Zephaniah Turner, Jr. |- |}
Template:Speakers of the Virginia House of Delegates