Park Roads: Mount Rainier's master plan, begun in 1926, was the first National Park Service (NPS) master plan to be conceived and it was highly influential in the conception of master plans for other parks. The NPS landscape division produced master plans that preserved parks while addressing the needs of all the park's users and constituencies. The Mount Rainier master plan envisaged the infrastructure of the park as a system of scenic highways and developed areas, to be known as rustic park villages, which would accommodate visitors but at the same time delimit their vehicular access within the park. The master plan was drawn up in the 1930s and executed in the naturalistic style of landscape architecture and rustic style of architecture. The circulation patterns at Mount Rainier, which include a sophisticated hierarchy of roads and trails are a key part of the early master plan. Trails, utility roads, and scenic highways were each conceived as independent but integrated systems, and each type had its own cross section, geometric specifications, maximum allowable grades, and typical construction details. Each circulation system has its own sheet in the master plan showing the extent of road or trail development throughout the park. In practice, these circulation systems were effectively interrogated, creating a complex and efficient total system of circulation that assured each set of circulation needs were met in a carefully coordinated way. The main scenic highways in the park are Nisqually Road, West Side Road, Stevens Canyon Highway, East Side Highway (Route 123), Mather Memorial Parkway (HW 410), Yakima Park Highway, Mowich Lake Entrance Road, and Carbon River Entrance Road.

The first road to be built in the park was the Nisqually Road, constructed by the Army Corps of Engineer's between 1906 and 1916. However, it was not until the 1920s and 1930s that the major road construction work in the park was accomplished. The task of making the road layout in the master plan a reality was given to NPS landscape designers who worked in close collaboration with engineers from the U.S. Bureau of Public Roads (BPR). The interbureau agreement between the NPS and the BPR played a fundamental role in guaranteeing the aesthetic quality and technical excellence of roads within the park. Under this arrangement, which began in the 1920s and was formalized in 1926, the NPS outlined the general location and aesthetics of each project. BPR engineers then conducted surveys and developed construction drawings for NPS approval. Great care was taken to ensure that upgrades to existing roads were constructed as sensitively as possible and the new roads and facilities harmonized with their local environment. The successful master plan for Mount Rainier quickly became a blueprint for other parks during an era that is widely regarded as the "Golden Age" of national park road building.

All of the roads within the park continue to define the automotive circulation of the park. That circulation pattern, approved by Horace Albright in 1929, describes a great loop from the Seattle/Tacoma area, via the Mountain Highway to Ashford, entering the park at Ashford, proceeding from Paradise via the Stevens Canyon Highway to the southeast corner of the park, and exiting the park to the north via the Mather Memorial Parkway, returning to the Puget Sound communities via Route 410. Only the southern and eastern sides of the mountain, therefore, are traversed by this primary corridor; all other roads, including the West Side Road and the Yakima Park Highway, are cul-de-sacs and therefore side trips.

In 1997 the park roads were included in the National Historic Landmark (NHL) District designation for Mount Rainier National Park. The NHL District follows a corridor 30' from the centerline of the roads on either side, and includes ditches, swales, and all other historic structures associated with road construction. Bridges along the roads are counted as additional individual structures. The NHL District is nationally significant for its association with the events of early NPS master planning (criterion A) and the design style of naturalistic landscape architecture (criterion C) perpetuated by the NPS in the period between the First and Second World Wars. The period of significance for the NHL District of Mount Rainier National Park is 1906 - 1957, broadly incorporating the earliest and latest rustic period development in the park.

Today, the historic circulation system of the park is remarkably intact. In most instances, postwar construction has had very limited impacts on the park's historic circulation system. The park has historically drawn large numbers of visitors and continues to be a major attraction due to the complimentary system of roads and trails that provide access to many remote areas within the park.

Stevens Canyon Highway: Stevens Canyon Highway is a historic road within the Mount Rainier NHL District. As one part of the early Mount Rainier National Park master plan, Stevens Canyon Highway is significant for its association with the national park system's earliest and most influential surviving master plan. It also takes its significance from its naturalistic landscape engineering as a scenic park highway that was artfully integrated with the natural landscape.

The 19-mile Stevens Canyon Highway was planned, designed, and constructed during the historic period, although construction was interrupted by World War II. When the project was resumed, it was completed according to the original plans. The workmanship, materials, and feeling of these portions of the road are consistent with the rest of the park's road system. The later portions of the road (between Stevens Creek and the Cowlitz Divide) are an integral part of the NHL District. Therefore the two bridges, Nickel Creek and Muddy Fork Cowlitz and one tunnel, Box Canyon, completed in the early 1950s, as well as the sections of roadway on which grading was completed at that time, are included as contributing resources in the NHL District. The construction of these later portions of road (masonry veneered, reinforced concrete arches, for example) is completely consistent with the design and construction completed in the 1920s and 1930s as part of the master plan for the park. Certain postwar portions of the later roadway (along Stevens Ridge and Backbone Ridge) employed sections of concrete viaducts to minimize excavation and scarring while traversing very steep hillsides. Although this construction is not typical of prewar park road design, even these sections are included in the NHL District because they are integral to the overall character of the road corridor, and are a logical extension of the principles of NPS road construction. Given that the centerline of the route follows the alignment of the road during the period of significance, and since almost all of the major structures associated with the road are original, it can be said to have excellent integrity overall to the period of significance.