Mercury, Nevada, is a closed city in Nye County, Nevada, United States, north of U.S. Route 95 at a point northwest of Las Vegas. It is situated within the Nevada Test Site and was constructed by the Atomic Energy Commission to house and service the staff of the test site. The specific site was known as Jackass Flats, NV and nearby Nevada Test Site 400. Today, the site is governed by the United States Department of Energy. As part of the test site, the town is not accessible to the general public. It was named after the mercury mines which flourished in its general vicinity a century before the town itself was established. The current population is unknown.