Irwin township represents an area within the Irwin township subdivision of the Tripp County (South Dakota),
which is not part of any official city, town or other place of the Irwin township subdivision.
This area is populated by approximatelly 25 people and occupies the area of 37 square miles - 1 square miles represent water areas.
Racial makeup of the population is : White (88%), Two or More races (12%) and Some Other Race (0%).
The male part of the population has a median age of 42 and the “median female” is 43 years old.
Statistical data for the Irwin township based on the 2010 U.S. Census