The forty bridges in this thematic study are the best of their types which were still in use on the state and county road systems in Wyoming when the study was completed in 1982. Selected from a statewide survey of all functional vehicular trusses and arches using a specific evaluation criteria and methodology, most represent superlatives of their generic engineering types (i.e. truss configuration and connection types) while typifying bridgebuilding and transportation trends in the state. All were built in the first three decades of the twentieth century (1905-1935). Although bridges were put up during the earlier periods of overland wagon emigration, they had not begun to proliferate in the state of Wyoming until the early twentieth century with the emergence of the automobile as a principal form of transportation. All the listed bridges display a remarkable homogeneity of construction and operational histories. Generally, county-built trusses were contracted through competitive bidding among several Midwestern bridge erectors and built from standardized designs using prefabricated components. After creation of the Wyoming Highway Department in 1917, the role of the counties in truss bridge construction diminished. The later highway department bridges were typically designed from standard plans maintained by the department and built by local contractors from components fabricated in the same Midwestern foundries.

One feature that all steel truss bridges shared was their versatility. Quickly erected, they could also be dismantled and moved if necessary. Many county road bridges in Wyoming had begun service as railroad bridges, sold or given to the counties as obsolete structures. Similarly, early highway bridges which had become unsuitable to handle increasing volumes of traffic were sometimes replaced with new trusses, with the older bridges demoted to places along less traveled roads. After World War II, new trussbuilding was rare in Wyoming. Today trusses have been largely superseded by more sophisticated engineering designs and are seldom erected. The remaining highway and roadway truss bridges are remnants of past technologies, whose numbers are continually dwindling through attrition.

Spear-O-Wigwam Ranch is significant for its association with dude ranching in the Bighorn Mountains from the 1920s through the early 21st century. The ranch is also an excellent example of rustic style dude ranch architecture, especially the multi-sided lodge in the shape of the ranch’s brand-a spear extending from a wigwam. Dude ranching activities began at the property in 1923 by Willis Spear a prominent cattle rancher who served briefly as a Sheridan County Commissioner, then later was elected to serve in the Wyoming State Senate from 1918 to 1932.

St. Luke's Episcopal Church was built in 1889 of red brick, in the Gothic Revival style of architecture. The church displays many noteworthy architectural features, and is considered one of the best examples of the Gothic Revival architectural style in the state of Wyoming. The interior plan, with a small narthex, long narrow nave, chancel elevated by two steps, sanctuary elevated by two more steps, typifies the plans of small Episcopal churches throughout the country. The cornerstone was laid in 1889 by the Masonic Lodge of Buffalo. The builder, Thomas Hutton, used red brick made by the Curran brothers in their brickyard on the west side of town.

Also known as the Sussex Community Hall, this building has been the focal point of the small rural Sussex community for over 80 years. Constructed in 1914, the Sussex Community Hall is located on the north bank of the Powder River in southeast Johnson County. It was originally constructed as a combination grocery store/post office/dance hall housed in one large room. The store and post office were located at the east end of the building and the dance hall on the west end. In the late 1920s, the store and post office moved to a renovated garage east of the present building and the entire room became devoted to a dance hall/community center. Towering old cottonwood trees dwarf the modest building that is still considered the heart of this rural ranching community located twenty miles east of the more famous town of Kaycee, Wyoming which achieved notoriety for its role in the Johnson County War. The Sussex Community Hall was an active place for many years, hosting such varied activities as Halloween, Christmas and Thanksgiving suppers; Mother-Daughter banquets; ''harvest suppers''; wedding receptions; picnics and barbecues; home-talent plays; school programs; and annual meetings of the Sussex Irrigation Company. It still serves as the polling center during local and general elections.

The TA Ranch is significant as the site of the famous Johnson County War of 1892. The ranch is also important for its contribution to the development of cattle ranching in Johnson County. The TA Ranch was established in 1882 and is one of the first ranches in Johnson County. The TA Ranch is the only remaining Johnson County War battle site which retains its associated buildings and structures. The marks of the battle are still evident in the barn and the ranch house; battle trenches still exist where both the defenders of Buffalo and the ''invaders'' entrenched themselves against the shower of bullets. Following the 1892 battle the ranch expanded. Many buildings were added to support the large amount of manpower and livestock necessary to the pre-mechanization way of life.

The Union Congregational Church, one of the first two churches established in northern Wyoming Territory and the first church in Buffalo, was incorporated in 1884, the same year the town of Buffalo was chartered. Situated on the top of a steep hill, the church was a plain, gable-roofed, rectangular, frame structure. The members of the church had constructed a building large enough to hold 200 people and to serve as a center for religious and social activities. Besides religious services, this structure housed dramatic production, concerts by local talent, old-fashioned spelling bees, and other gatherings. The present configuration of the church is the result of a remarkable plan formulated by the Reverend Charles Gray Miller and put into effect in 1911-1912 to enlarge the church. A basement was constructed on the lower slope of the hill to the west and the church was moved onto it. The parsonage, which was built in 1910, is just northwest of the church and on a level with the west side of the basement.

The site is a bison jump comprised of a large, intact bonebed and associated cairn drive lines. Four radiocarbon dates place the site’s use during the Late Prehistoric Period in Wyoming, potentially by the ancestors of the Crow. The site’s bonebed contains a thick deposit of bison bone, abundant charcoal, and numerous chipped stone artifacts. The associated drive lines contain a total of 67 stacked or single stone cairns. Previous investigations have established the presence of at least one jump event, but deeper, as yet unexcavated bone deposits may exist at the site.

National Register form available upon request.