Lake Guernsey State Park developed during the early 1930s on federal land that had been purchased for the North Platte River Project by the Bureau of Reclamation. The reservoir was first filled in 1927 following construction of the Guernsey Dam and Power Plant. The park, located near Guernsey in eastern Wyoming, features a lakeshore drive and a skyline drive, extensive original trails, and an exceptional group of Civilian Conservation Corps era buildings and features constructed of roughly worked local sandstones.

Worn from two to six feet into an eroded sandstone ridge located on the south side of the North Platte River about one-half mile south of the town of Guernsey, Wyoming, the Oregon Trail Ruts provide striking physical evidence of the route followed by thousands of Americans in their migration westward across the Plains between 1841 and 1869. The first recorded use of what was to become the Oregon Trail occurred in 1812, when Robert Stuart and six companions followed the route in returning to the East from Fort Astoria in Oregon. In the succeeding years, the route was used by numerous traders, trappers, and missionaries; but it was not until 1841 that the first wagon train, that of the Bartleson-Bidwell party, moved westward over the Trail. Over 100 emigrants followed the Trail west in 1842, and over 900, in 1843. In the ensuing years the numbers of emigrants steadily increased, and the Oregon Trail became a clearly defined and deeply rutted road across the country. With the completion of the Union Pacific Railroad in 1869, use of the Trail as an overland route to the Pacific rapidly declined, although sections of it continued to be used locally for many years. The combined effects of wagon wheel wear and cutting to ease passage over a rough place in the road, these ruts near Guernsey are probably the most prominent along the Oregon Trail and are unsurpassed in their clarity and integrity.

Register Cliff consists of a soft, chalky, limestone precipice rising over 100 feet above the valley floor of the North Platte River. The horizontal features of the cliff were created thousands of years ago by the erosive action of the river waters cutting through layers of soft sedimentary deposits. Register Cliff is a link to the romantic era of overland migration in Western America. It was an important mid-19th century landmark along the route of travel to Oregon and California and a place where countless emigrants inscribed names, dates, origins and messages in the soft limestone cliff faces. Although inscriptions are found at numerous places along the trail, Register Cliff represents one of the three best known ''registers of the desert'' -- the other two being Independence Rock and Names Hill.

Register Cliff was the first night camp west after leaving Fort Laramie. Under the shadow of the chalky bluffs on the south bank of the Platte River the emigrants paused to set up camp, to pasture their animals, and to rest and recoup from the hardships of trail travel. This stopover gave the wayfarers time to record the names and dates which have now become an enduring aspect of an historic era. Many of the names and dates at Register Cliff relate to the peak years of travel along the trail during the 1840's and 1850's. Several states are well-represented in the carvings with Ohio seemingly in the majority. It is likely that the cliff and its surroundings were a familiar stopping place during the fur trade era but inscriptions dating to this period that may have existed at one time have apparently weathered away. The earliest known date reads: ''1829 This July 14'', perhaps placed there by some French trapper or explorer to commemorate Bastille Day. One unusual series of names, representing three generations of Register Cliff scribes, are those of T.H. Unthank dated 1850, O.N. Unthank, 1869, and O.A. Unthank, 1931.

Charles A. Guernsey, a pioneer cattleman after whom the town of Guernsey, Wyoming is named, established his ranch buildings a short distance from Register Cliff in the 1890's. Guernsey's successor to the ranch, Henry Frederick, donated the site to the State of Wyoming to be preserved as a memorial to the spirit and accomplishments of the pioneers.