The US government built a massive nuclear weapons complex during the 1940 s and 1950 s. The conventional wisdom is that these facilities are sources of jobs and income for the surrounding regions. Recent research challenges the conventional wisdom, finding that areas with the weapons facilities have higher unemployment rates, attract less than their share of private sector investment, and suffer from the stigma of environmental contamination. We find evidence that supports both contentions and shows that geography and the built environment, including public infrastructure, are often key determinants of the economic impact on surrounding areas. Using a control group method, we studied 22 counties located within 10 miles of the five most prominent nuclear weapons sites. Focusing on the most recent quarter century, we identified large increases in employment, population, and income beginning in the mid-1970 s in the counties hosting the largest facilities. Most of the counties adjacent to the host counties also manifested economic impacts larger than their control counties, but some did not. The lagging counties tended to be physically isolated and lacking in public services and other attributes that tend to attract residential and commercial development.