Henry Armstrong (September 11, 1841 – August 2, 1904)[1] was an American politician who was a pioneer of Idaho.

Armstrong served in the 2nd Wisconsin Cavalry Regiment from December 1861 to October 1865, reaching the rank of sergeant.

[1][2] He came to the Idaho Territory as a miner, operating a mine in Galena Gulch, in Alturas County, by 1882.

[5] He was elected as a Republican to represent short-lived Logan County, first at the Idaho Constitutional Convention in 1889,[6] then in the first session of the Idaho House of Representatives, which lasted from December 1890 to March 1891.

[7][8] Armstrong was a member of the Populist Party in the late 19th-century, serving as a delegate at the party's 1896 and 1900 state conventions and losing an election for probate judge of Blaine County in 1898.