Between 16 July 1945 and 23 September 1992 the United States of America conducted (by official count) 1054 nuclear tests, and two nuclear attacks. The number of actual nuclear devices (aka "bombs") tested, and nuclear explosions is larger than this, but harder to establish precisely. Some devices that were tested failed to produce any noticeable explosion (some by design, some not), other "tests" (by official definition) were actually multiple device detonations. It is not clear whether all multiple device tests have yet been identified, and enumerated.
   see our Nuclear Age Timeline section 

These pages focus principally (although not exclusively) on the period from 16 July 1945 to 4 November 1962, the era of atmospheric testing*. There are a number of reasons for this. These early years marked the height of the Cold War, when the U.S. nuclear weapons establishment came into being, when the major breakthroughs in weapon design occurred, and when the most severe effects of nuclear testing were felt around the world. During this period test series were grand operations, involving huge numbers of people, and each often with a set of clear objectives. The era of atmospheric testing is also the period for which the most information is available. When tests were exploded in the open, everyone could collect data on what was being tested. When the tests went underground, testing became routine, and information about what was being tested went underground too. And of course, we can't have a gallery without pictures- and atmospheric tests are the only ones for which pictures exist.

* There were actually a few surface tests included in the official test count conducted after 4 November 1962. These were a series of zero yield tests of plutonium dispersal conducted in 1963, known as Operation Roller Coaster.