In the Great Lakes Region
, Chamberlain is located in Brule County
(of which it is the county seat) southeast of Pierre
next to Oacoma
, with which it shares a chamber of commerce. The two cities lie along I-90 on the banks of the Missouri River
and Lake Francis Case
Chamberlain-Oacoma rests in the heart of prime pheasant and grouse, deer and waterfowl country and boasts one of the highest annual bird harvests.
The population estimate for July 1, 1998 was 2,411, an increase of 64 since 1990.