Nellis AFB is today one of the Air Force's largest, most important bases. It's a long time since Nellis was Las Vegas Airport, just a small, dirt runway with a support shack and water well for Western Airlines.

In the late 1930s it was becoming increasingly clear that American involvement in war in Europe or Asia was likely, and that air power was vital to US military needs regardless of whether war came or not. In 1940 the US Army Air Corps was actively building air facilities around the USA, and had identified a need for an aerial gunnery base for training and testing. Nevada was a leading candidate, with large areas of desert wasteland, allowing virtually unrestricted gunnery backfields, and remote enough to be secure from civilian enemy observation. In 1941 the underdeveloped Las Vegas Airport site was selected and construction began, using Work Progess Administration barracks, Civilian Conservation Corps equipment and fuel, and McCarren Field for air service, Las Vegas Airport being too small and primitive to use.

Housing for 3,000 servicemen was begun immediately, along with runway improvement, hangars and other airfield buildings from scratch. The new airfield was activated two weeks after the Pearl Harbor attack, as Las Vegas Army Airfield, with initial training aircraft and B-10 bombers. Gunnery training was extremely basic to start; trainees started in the backs of trucks, with fixed-arc mounted shotguns, practicing their aiming skills in ground range courses. After ground training, trainees were flown in bombers for gunnery practice against towed targets. Five weeks of training, and the class was rotated to their next training station. After some months, Las Vegas AAF gained some B-17 bombers for training, and training equipment was repeatedly improved over the course of the war, including hit score flash lamps, frangible range safety bullets, and gun cameras for training study.

Las Vegas AAF was constantly growing in this period, and added several auxiliary fields, including one that later became Creech Air Force Base, and another later known as Groom Lake. B-17 training continued to March of 1945, when training shifted to B-29 Superfortresses, which continued to war's end in August 1945. With the end of the war, Las Vegas converted to troop return, separation and demobilization. This kept the base occupied for most of the next year, but the base was inactivated at the end of 1946.

This inactivation lasted only eight months; Las Vegas AAF was reactivated in August of 1947, to be used as a training center for bomber crews; this suffered organizational problems, and not until January 1948 did Las Vegas Air Force Base functionally reopen; ongoing problems prevented training from beginning until March 1949. The Air Force had a need for advanced fighter pilot training, and the initial training out of Nellis was for P-51 Mustangs; the first class of trainees were soon called to service in the Korean War. Soon after, Las Vegas AFB was renamed Nellis Air Force Base, after Lt. William Harrell Nellis, training converted to jets, and to fighter-bombers. The base was found to need improvement to base jets and lacking important base infrastructure, and from 1951 to 1958 the base underwent several stages of reconstruction. Runways were strengthened and lengthened, permanent housing, including married personnel housing, was added.

In 1954 Nellis finished a conversion from bomber gunnery training to fighter gunnery training, a mission it continues. At the time the training squadron was named the USAF Fighter Weapons School, today called the USAF Weapons School, reflecting changes in air combat. Starting in the early 1960s Nellis weapons training included air-to-air gunnery, rocketry, conventional and nuclear bombing, aerial refueling, and combat navigation, since expanded to air-to-ground and air-to-space tactics. Concurrent with the weapons school, Nellis also became the primary base for fighter tactics, flying, and procedure development and refinement. With such a concentration of fighter pilot skill, Nellis also became a testing site for new fighters and other aircraft, and the evaluation center for foreign aircraft, starting in the 1960s. This evaluation led to the establishment, in the 1970s, of the 414th "Red Flag" combat training squadron, one of the finest (then) Soviet fighter squadrons in the world, using Soviet hardware and tactics, as best as could be simulated, for advanced training. Another natural result of all of this fighter pilot skill concentrated in one base was the reassignment of the USAF Thunderbird demonstration squadron to Nellis in the early 1950s.

The success of the Red Flag program prompted the Silver Flag ground security training program, challenging the skills of USAF security troops, and Green Flag West, a joint air-ground training exercise conducted with the US Army.

Nellis is also home of the Nellis Air Force Range, formally called the Nevada Test and Training Range, the site of a great deal of aerial gunnery and bombing training and testing, and the Nevada National Security Site (formerly the Nevada Test Site), where a significant number of US nuclear weapon tests were carried out in the 1950s and 1960s, and still the site of various large non-nuclear tests.

Nellis AFB is also the site of the Nellis Solar Power Plant pilot facility, part of an effort to shift military facilities away from foreign and finite fuel sources. The Nellis Solar plant generated an above-goal 32 gigawatts of power in its first year of operation, and continues to harvest locally abundant solar energy.