We measured vehicle traffic volume at two locations on US Highway 2 along the southern boundary of Glacier National Park during 2012 and 2013 and then compared results to those collected during 1999 through 2001. We show that traffic volumes have increased substantially in the 11 years between counts and that the increases are most dramatic during the hours in which grizzly bears (Ursus arctos) are most likely to cross the highway. Over the preceding decade, grizzly bears have lost two hours of suitable crossing opportunity and will, should observed growth rates and traffic continue, lose an additional three hours within five years
