Response review

I'd be happy to help you figure out who represents South Dakota's at-large congressional district (SD-AL). Let me search for the current information.
Your U.S. representative in South Dakota's at-large congressional district (SD-AL) is **Dusty Johnson**.

Since South Dakota has only one congressional district, 
South Dakota's at-large congressional district is the sole congressional district for the state of South Dakota, and it is currently represented by Dusty Johnson
. He is a Republican, as indicated by his official designation as 
Rep.-R-SD-At Large
.

A quick note: South Dakota's at-large seat covers the entire state, so all South Dakotans share the same U.S. representative regardless of where they live in the state.