About the Trinity Site

Trinity Site, where the first atomic bomb was tested at 5:29:45 a.m. Mountain War Time on July 16, 1945.
The 51,500 acre area was declared a National Historic Landmark in 1975. The landmark includes base camp, ground zero, and the McDonald ranch house where the plutonium core to the bomb was assembled. Visitors to a Trinity Site Open House see Ground Zero, “Jumbo” bomb casing, the McDonald House, one of the old instrumentation bunkers, historical photos, a Fatman bomb casing, and part of the original crater left by the explosion revealing “Trinitite”. (Greenish colored glassy substance formed by the heat and pressure of the explosion).

Trinity Site is open the first Saturday in April and October. The Stallion Gate Hours are from 8:00 a.m. to 2:00 p.m. and the Trinity Site closes promptly at 3:30 p.m. The is a Free event, open to the public and no reservations are required. For more information please visit https://www.wsmr.army.mil/Trinity/Pages/Home.aspx

Tour Entrance Gates & Times

  • Alamogordo Tour: Line-up begins at 7:00am at the Tularosa High School Athletic Field parking lot. From Hwy 54/70 in Tularosa, turn west on Higuera St. (at the Tulie Freeze). Proceed to Riata Rd. Turn right and follow to the athletic field. The tour will enter the missile range through the Tularosa Gate at 8:00; arrive at Trinity Site around 10 a.m. The caravan must stay together. There is no stopping in route to Trinity Site. Departure from Trinity Site will begin at 12:00 p.m. Those who wish to stay longer may exit through the Stallion Gate.
  • Stallion Gate Entrance: Open 8:00 am to 2:00 pm. Visitors are allowed to enter and exit unescorted anytime during these hours. The Stallion Gate is located on U.S. highway 380, 12 miles east of San Antonio, NM and 54 miles west of Carrizozo, NM.
    Schmidt/McDonald Ranch House: The Schmidt/McDonald Ranch House is part of the National Historic Landmark and is where the Plutonium core of the bomb was assembled. It is located two miles southeast of Ground Zero. In 1984, the Schmidt/McDonald Ranch House was restored to its 1945 condition through the coordination effort of the U.S. Army Department of Visitors wishing to include the ranch house in their tour. TRANSPORTATION IS PROVIDED FROM TRINITY SITE TO THE SCHMIDT/MCDONALD RANCH HOUSE AND BACK TO TRINITY ONLY.

Alamogordo Tour Information

The following information is provided to make your drive to Trinity Site safe and enjoyable:

  1. Photo Identification Required- No Weapons Allowed
  2. Everyone should ensure they have a full tank of gas and a spare tire prior to starting the tour. The distance is 85 miles one-way to Trinity Site.
  3. Most of the time you will be on a restricted Army post. Please follow the directions of the Department of Defense Police. Also, leave your cameras stowed until you reach Trinity Site.
  4. Slow down for animals on the shoulder of the road. Do not stop unless you have to. Sudden stops create a situation that can get your car rear-ended.
  5. The return caravan is scheduled to leave the Trinity Site parking lot at 12:00 pm. Please be in your vehicle and ready to leave by this time.
  6. At 12:00 pm follow the police vehicle with the flashing lights, south out of the parking lot- the same way you came in.
  7. Use caution when you pull out. Take your time. The caravan will be organized down the road away from the parking area and no amount of jockeying is going to get you home sooner.
  8. If you wish, you may leave through the Stallion Gate at anytime during your visit. There are signs marking the way and there is a map on the back of the Trinity Site brochure. It is about 115 miles back to Alamogordo via this route.

No charge is made for the tour and no reservations are necessary.

While the degree of radiation is extremely low, less than that of a radium dial watch, pregnant women and parents of extremely small children (babies in arm) are advised that the decision to visit the actual site is of the OWN RESPONSIBILITY.