View Full List of National Register: Wyoming Listings

The site of ''The Prairie Mass'' is on a broad open plain atop a high bluff overlooking the Upper Green River valley. The Prairie Mass represents one of the earliest occurrences of organized Christian religious ceremony to take place in the Rocky Mountain region and the first Catholic Mass to be held in the area that now comprises the State of Wyoming. This Mass, which took place on Sunday, July 5, 1840, is also a symbolic reminder of the missionary movement on the Western Frontier that so greatly influenced the cultural transition of many of the American Indian tribes. The Mass was conducted by Reverend Pierre DeSmet.

After several missions among the Indians, Father DeSmet started out from St. Louis on March 27, 1840 to begin work among the Flathead tribe located in the Upper Missouri valley. Joining an American Fur Company caravan, Father DeSmet journeyed up the valley of the Platte River past Fort Laramie, Independence Rock, over South Pass, and paused briefly at the annual fur trader's rendezvous in the shadow of the Wind River Mountains on the Upper Green River. Father DeSmet added a new element to the rendezvous by delivering sermons and lectures, holding religious ceremonies, and participating in council discussions with various groups of Indians. It is estimated that 2,000 Indians, trappers and traders were present to hear the first Mass ever celebrated in the Rocky Mountains. The congregation was addressed in both French and English with the Indians spoken to through an interpreter. The Canadians sang hymns in French and Latin and the Indians in their native tongue. When the service concluded, the French-Canadians christened the site ''La Prairie de la Messe'' -- the Prairie of the Mass.