This study examines path flows for road networks. Path flows sum individual route choices from individual travelers, associated with specific path objective. We estimate these flows for each cost factor of auto travel: time, safety, emission, and monetary costs, as well as their composite, internal and full cost of travel. For each factor we find the route with the minimum cumulative cost. We further explore the extent to which each cost factor contributes to explaining the observed link traffic flows given an estimated home-to-work demand pattern. The results of the Minneapolis - St. Paul metropolitan area indicate that flows from multiple path types, associated with different internal cost components, along with distance, provide the best fit.