Discovery of diamondiferous kimberlite in northwestern Canada, and occurrences of similar intrusions and alluvial diamonds elsewhere, suggest North America is fertile ground for economic primary diamond deposits. Using a Diamond Exploration Geoscientific Information System (DEGIS) to develop an exploration model, we have identified four areas of permissive terrain in the north-central United States: Wisconsin-Upper Peninsula of Michigan, southeastern Wyoming, North Dakota-Minnesota, and northwestern Iowa. Permissive areas feature lithosphere that is >1.6 billion years old and 150 km thick; and prospective zones within this terrain contain point and linear features that are associated with kimberlite and lamproite emplacement.