As with bus transportation, the only statistically reliable economic effect we found was that greater population density leads to greater route coverage. Transit authorities, whether popularly elected or appointed by the governor, tend to curtail route coverage, while local entities that receive federal tran- sit money tend to expand it. American riders also expand route coverage. As with bus transportation, economic considerations play a greater part in determining frequency of rail service than in determining route coverage. Increased population density increases frequency, while greater operating expenses and broader route coverage decrease it.
Government subsidies increase frequency.
Some policymaking entities have distinct effects on frequency. Governor-appointed transit authorities tend to increase it, but local entities decrease it. Again, upper middle-income riders clearly benefit from urban rail systems because frequency increases when their share of patronage increases. Frequency decreases, however, when the share of lower middle- . . income rlc ers increases. In the case of bus service, we suggested that the finding that increases in the share of black and Hispanic riders curtailed route coverage could reflect the resistance that some communities have toward expanding route coverage because of their fear of attracting more crime.