The site selection for the Manhattan Project's main bomb laboratory involved several criteria. One criterion was that the site needed to be at least 200 miles from any coastline or international border. It also needed to be sparsely populated, both to maintain security and protect against civilian casualties in the event of an accident. In late 1942, a small boys school near Los Alamos, New Mexico, was identified as the best site. To this location, J. Robert Oppenheimer brought 6,000 scientists and technicians who worked in total secrecy until the first atomic bomb was dropped on Hiroshima. Following the end of World War II, Los Alamos continued to be a research center. It is one of two laboratories in the United States where classified work involving the design of nuclear weapons is carried out. The other is Lawrence Livermore National Laboratory in Livermore, California. Like Livermore, Los Alamos is operated by the University of California. It is presently the largest employer in northern New Mexico, with nearly 9,000 workers and a budget of more than $1 billion annually.