Summer tours at Minuteman Missile National Historic Site have been so popular that all of the reserved slots for June and July have been booked, according to a National Park Service news release.

Potential visitors have been calling since April 2, when reservations for the guided tours began. Tours are conducted twice daily at 9 a.m. and 1:30 p.m. Monday through Friday, and are limited to 12 people per tour.

The site has seen an increase in visitation of 60 percent during the first four months of the 2007 season.

Due to the increase in visitation, the site will be offering two visitor opportunities for the upcoming season in which no reservations will be required.

The first opportunity will be two open houses on June 7 and 21 (the first and third Thursday's of the month). They will take place in the morning from 8:30 a.m. to 11:30 a.m. These open houses will allow more visitors an opportunity to tour the site. This tour will include a visit to the underground launch control center.

The second opportunity will be the opening of Launch Facility (missile silo) Delta-09 to drive-up visitation from 8 a.m. to 11 a.m. Monday through Friday during the summer. Visitors will be able to view the Minuteman II missile on display at this once operational silo.

A ranger will also be stationed at the silo to answer questions.

Visitors on tours are currently escorted through the topside structure and control capsule 30 feet below at Delta-01, a former launch control facility that housed missile crews from the 44th Missile Wing at Ellsworth Air Force Base. They also travel to Delta-09, a missile silo containing a deactivated Minuteman II missile. Tours are approximately two hours in length and will continue through Labor Day.

Through September two tours are offered daily at 10 a.m. and 1:30 p.m. Monday through Friday. Reservations for the remaining summer slots should be made well in advance by calling the Minuteman Missile NHS Project Office at 605-433-5552. The office will begin taking reservations for September on June 4.

Minuteman Missile NHS was established by Congress in 1999 to tell the story of the Minuteman ICBM system, including the development of the system, the personnel who served at the 1,000 sites throughout the upper Great Plains, and the impact of the system on nearby communities.

Following the transfer of the property from the U.S. Air Force in September 2002, the National Park Service began preparing the site for public tours.