The median income of Marshall County residents was an inflation-adjusted $30,314 per year. Marshall County had 1,813 households in 2017, with a population of 4,759.
The county with the highest median resident income in the state was Lincoln County. Lincoln County's median income was $37,691 per year after adjusting for inflation – $7,377 more than Marshall County. It had 18,736 households in 2017 and a population of 53,147.
Oglala Lakota County had the lowest annual resident income among counties in South Dakota, with a median income of only $12,372 per year. That was $17,942 less than the median income in Marshall County at the time. Oglala Lakota County had 2,920 households in 2017 and a population of 14,291.
The table below shows the state's counties ranked by median annual resident earnings in 2017.