Abraham Brookins Gardner was born in Pownal, Vermont, on September 2, 1819.

He graduated Phi Beta Kappa from Union College in 1842, where he was a member of the Delta Upsilon fraternity.

Gardner then studied law and became an attorney and business owner in Bennington, Vermont, including serving as President of the Eagle Square Manufacturing Company and the Bennington and Rutland Railroad.

[2][3][4][5] A Republican, he was Register of Probate for the Bennington District from 1848 to 1857, State's Attorney from 1855 to 1857, and Vermont's Banking Commissioner from 1859 to 1860.

[8][9] He was Lieutenant Governor from 1865 to 1867, and also served as a member of the Republican National Committee.