Northern Arizona in the southwestern United States has deep ties to the U.S. space agency, NASA. Every moon-walking astronaut in the Apollo program trained there. Even a crater on the moon was named in honor of the city of x, Arizona. x is a public lands historian at Northern Arizona University. It's really cool to think that this relatively small town in northern Arizona played such a big role in the Apollo missions, he said. x often receives credit for Arizona's role in the moon missions. He once worked as a scientist for the U.S. Geological Survey. In 1963, he moved the agency's astrogeology office to x. It was not long after the move that x guided astronauts such as Neil Armstrong and x on visits to meteor crater near x. He wanted to make sure that the Apollo program would include geology. x is a research geologist at the Astrogeology Science Center. She is working with NASA's 2017 class of astronaut candidates. The space agency plans to send them to x later this year for field training. It will be pretty inspiring for them, said x. It's inspiring for us being involved in this. x is among many cities celebrating the 50th anniversary of the first moon-landing on July 20, 1969. It is celebrating the anniversary with guided tours, demonstrations, talks and moon-related food and art. Retired x staff, geologist x plans to celebrate the big event by wearing a turquoise x tie. x tie is a kind of string worn around the neck. It is common in the western half of the United States. The x tie distinguished x's Arizona crew from others who worked on moon missions. x was at NASA's mission control in Texas in 1969, watching black and white images from Apollo 11 when bending over a map. I was just trying to do the best I could with the primitive tracking ability we had in those days, he said from his home in x. There, he has a picture of an area on the moon that Apollo 15 astronauts called x Hill. Arizona has approved a nomination to list several of the training areas near x on the National Register of Historic Places. Federal approval is still needed.