WASHINGTON, July 16. /TASS/. The first ever nuclear weapons test caused radioactive contamination of an area of about 2,600 square kilometers in the US, according to declassified US government documents released by the National Security Archive at George Washington University in Washington, D.C.

The documents show that the Trinity nuclear test, which was conducted on July 16, 1945 at the White Sands Proving Ground in New Mexico as part of the Manhattan Project contaminated more than 1,000 square miles (more than 2,600 square kilometers) of the state's territory. Some of the fallout from the test spread as far north as Canada.

Six weeks after the test, "fairly high radioactivity was observed on the ground surface over an area about 100 miles (161 km) long and 30 miles (48 km) wide," according to a declassified report from the Los Alamos National Laboratory. The report also acknowledged that "gamma radiation, measurable but of very low intensity, was detected in Santa Fe (New Mexico), Las Vegas (Nevada), and even Trinidad (Colorado), about 418 km from the detonation site".