The following table shows the population history for various towns of O'Brien County.
For information about the population in 1880, see U.S>Federal Census Collection on Ancestry.com.

Year	Archer	Calumet	Hartley	Paullina	Primghar	Sanborn	Sheldon	Sutherland	Other	County Total
1890			519	510	519	1075	1478	490	?	?
1900		113	1006	617	814	1247	2282	722	10184	16985
1910	351	242	1106	796	733	1174	2941	664	9255	17262
1920	184	266	1306	987	921	1497	3488	876	9526	19051
1930	150	249	1272	1013	962	1213	3320	802	9428	18409
1940	178	274	1503	1230	1081	1344	3768	875	9040	19293
1950	167	250	1611	1289	1152	1337	4001	835	8329	18970
1960	209	225	1738	1329	1131	1323	4251	883	7751	18840
1970	134	219	1694	1257	995	1465	4535	875	6348	17522
1980	134	212	1700	1224	1050	1398	5003	897	5354	16972
1990	145	160	1632	1134	950	1345	4904	714	4502	15444
2000	126	181	1733	1124	891	1353	4914	707	4173	15102