Blair was elected circuit clerk in 1848 and served until 1854. He studied law. He was admitted to the bar and commenced practice in Canton, Missouri, in 1854. He served as delegate to the Republican State convention in 1870.
Blair was elected as a Liberal Republican to the Forty-second Congress (March 4, 1871-March 3, 1873). He was not a candidate for renomination in 1872. He resumed the practice of law and also engaged in agricultural pursuits. He died in Monticello, Missouri, March 1, 1904. He was interred in Forest Grove Cemetery, Canton, Missouri.