[3] Sioux also had a sister, Frances Louise Grigsby (later Mrs. George Edwin Robinson).

Grigsby was elected to the South Dakota House of Representatives in 1937 for Minnehaha County, and he served for two years, until 1939, when he was elected to the South Dakota State Senate, where he served until 1945, when he was named lieutenant governor.

[2] He had originally planned to run for the state senate again in 1945 but promptly withdrew his candidacy when he was nominated as lieutenant governor.

[4] Active in the Minnehaha County, South Dakota, American Bar Associations and state Taxpayers' Association, Grigsby was one of the more well-known Republicans in South Dakota, even being crowned "Mr. Republican" of the state in 1955.

An obituary of him at the time lauded him in that "his career ... [had] paralleled the development of his city and state".