The residents of this town of dairy and cattle farmers did not know it then, but half a century ago, northern winds blew radioactive fallout into southeastern Idaho when the federal government set off about 90 nuclear bombs at its Nevada test site near Las Vegas.

There is not any doubt that Emmett, population 5,500, and other towns in four Idaho counties were exposed to high levels of radiation from the open-air atomic bomb blasts, receiving among the highest doses of a radioactive chemical that has been linked to increased risk for thyroid cancer. The National Cancer Institute in 1997 released a detailed study and a map plotting the locations of the fallout across the country, ranking concentrations of Radioactive Iodine-131, an isotope released when a nuclear bomb is detonated, from Nevada to upstate New York. The study put the four Idaho counties - Gem County, which includes Emmett; Lemhi; Blaine; and Custer - and one in Montana at the top of that list.