“…Most notably, the drug abuse research literature, as it relates to the topic of spatial accessibility, has largely relied on administrative geographic units, such as states, counties, and zip codes (e.g. Archibald, 2008; Beardsley, et al, 2003; Fortney, et al, 1995; Jacobson, 2006; Perron, et al, 2010; Whetten, et al, 2006). More recently used geographies include census tracts, which are U.S. Census Bureau-designated geographies that average around 4,000 persons and provide greater geographic specificity (e.g.…”