The America's Byways® collection displays wide variations in the intrinsic qualities for which the byways were designated, as shown in Map 4 . Archeological quality is recognized as the primary intrinsic quality in only a few locations in Utah and the Four Corners area. Byways designated for recreational quality are scattered, and cultural quality is recognized primarily in the Mid-Atlantic to Midwest and Alaska. Byways designated for historic, natural, and scenic quality are most broadly dispersed across the country.
The geographic patterns of the intrinsic qualities represented by the collection strongly suggest that the collection may not completely represent range and diversity of the qualities across the nation. These gaps may be due to a combination of factors, including the Program's "grassroots" philosophy, the nomination process, and inherent overlaps among the intrinsic qualities.
One of the primary reasons for the unequal dispersion of designated byways across the country has to do with the National Scenic Byways Program's internal philosophy. Since its outset, FHWA has consciously managed the NSBP as a grassroots program in which local sponsors drive a byway's nomination. Although FHWA has actively reached out across the nation to promote the Program, decisions about whether to have a State or Indian tribe program and, if so, what routes to include are left completely in the hands of State agencies, Indian tribes, and local advocacy groups. Thus the level of activity varies from State to State and Indian tribe to Indian tribe depending on the existence and enthusiasm of individual State and Indian tribe byways programs and the ability of local organizations to identify potential candidate routes and marshal support for corridor management planning and nomination.
The Program's Interim Policy specifies that designation requires demonstration of "at least one" intrinsic quality for National Scenic Byways and "at least two" intrinsic qualities for All-American Roads. The Interim Policy does not specify a maximum number of intrinsic qualities that may be demonstrated. Over the years the nomination process has set a maximum that is equal to the minimum: that is, nominations for National Scenic Byway status may choose only one primary intrinsic quality as the basis of designation, and nominations for All-American Road status may identify only two such qualities. Again, the purpose was to encourage byway sponsors to focus on the most important attributes of their byways.
In practice, many byway nominations identify and describe more intrinsic qualities than the minimum requires. In part, this can be attributed to the interrelationships among the intrinsic qualities; an area with outstanding natural resources is likely to exhibit outstanding scenic and recreational qualities as well, and an area with historic importance over a long period of time can also have both archaeological and cultural resources.
There is a significant amount of overlap among the six intrinsic qualities. These six qualities have been well documented and identified by the individual byways in the collection. However, by their subjective nature they also have led to varied interpretations by the different byways. While unique resources support these varied interpretations, they also make it difficult to assess the overall diversity of the intrinsic qualities across the collection.