Belknap is located in southern Illinois in Johnson County
south of Marion
and the Kentucky state line along Highway 14 on the banks of the Cache River
about 10 miles north of the Ohio River
. The population estimate for July 1, 1998 was 137, an increase of 12 since 1990.
The town is in close proximity to the Cache River State Natural Area making it a hunter's heaven. The 14,000-acre facility (of which nearly 12,000 are huntable) offers a variety of game including deer, dove, duck, quail, rabbit, raccoon, squirrel, wild turkey and woodcock.