Trinity

The uranium and plutonium bombs progressed to the test stage. The search for a suitable test site began in May 1944. The test site required a relatively flat location, isolated from populated areas, and good weather. The test site needed to be within a reasonable distance of Los Alamos. Eight sites in four western states were visited.

One of the eight sites, the Jornada del Muerto Valley met the requirements. The 2,035,000-acre Alamogordo Bombing Range in south-central New Mexico was already under U.S. Government control. Located 230 miles south of Los Alamos, a portion of it was selected and code-named Trinity.

McDonald Ranch House

The George McDonald ranch house was renovated for a field laboratory. More

100-Foot Steel Tower

This tower of pre-fabricated steel was erected at Trinity site's Ground Zero. More

The First Atomic Test

The Trinity Device being lifted to the top of the 100-foot steel tower. Ground Zero is at the base of the tower. More

The First Atomic Device

On Monday, July 16, 1945, at 5:29:45 a.m., the first atomic device detonated at the Trinity Test Site. More

First Atomic Blast

The Trinity test succeeded. In late July 1945, President Truman reached the decision to use atomic weapons in the war with Japan and the Nuclear Age had begun. More