DOWNIEVILLE — People who reside here, along the western slope of the Sierra, have long dealt with difficult roads. They are both a curse and a source of pride to those windy, steep, and often slippery grades into and out of canyons on a regular basis.

For visitors to the area, reactions to the curves and the rugged terrain vary. Most enjoy the one- and two-lane routes and the scenic landscapes provided by CA-20, CA-49, CA-70, and CA-89, or the many dirt roads snaking along the slope. Not having to deal with city or freeway traffic is a welcome change of pace. Others, however, either can’t abide the slowness required by the roads, need Dramamine, or simply prefer civilization (“Where’s a Starbucks in this god-forsaken place?”). As for the inexperienced motorcyclists who took a curve a little too fast, their reactions are unknown.

But, how we feel about our roads fails to reflect our understanding of how rugged terrain - any location with a significant variation in elevation - impacts rural communities. To measure this, according to a publication released early this year, the USDA’s Economic Research Service first determined the location of rugged terrain and rugged roads within the U.S. To do this, researchers developed an Area Ruggedness Scale (ARS) and the Road Ruggedness Scale (RRS) and applied them to the geography within the nation’s 2010 census tracts.

What did they learn from their endeavors?

In 2010, the rural portion of residents living in level census tracts was 16.1 percent, while the rural portion living in highly rugged census tracts was nearly double that amount at 29.7 percent; the majority lived in urbanized areas.

Nearly 60 percent of residents in highly rugged rural locations lived in low-income census tracts compared with about 42 percent of rural residents in level census tracts.

The geographic distribution of ruggedness is similar for both the ARS and RRS measures, with some notable exceptions. RRS census tracts in the highest category are more numerous in West Virginia, Kentucky, and North Carolina, where dissected plateaus and ridges restrict road travel. This phenomenon also applies to the Cascade Mountains in Washington and Oregon. They are lower in average elevation compared with the Rocky Mountains, but the RRS shows traveling by road on level terrain through the Cascades may be more limited.