'Madison County, ID' definitions:

Madison -- U.S. County in Idaho

From: Gazetteer 2000
Name :
Madison -- U.S. County in Idaho
Population (2000) :
27467
Housing Units (2000) :
7630
Land area (2000) :
471.524653 sq. miles (1221.243194 sq. km)
Water area (2000) :
1.840271 sq. miles (4.766279 sq. km)
Total area (2000) :
473.364924 sq. miles (1226.009473 sq. km)
Located within :
Idaho (ID), FIPS 16
Location :
43.818344 N, 111.741490 W