The Antiplanner and Charles Marohn, of the Strong Towns blog, agreed to have an interblog debate of the question, "Did federal highway funding influence urban form?" Yesterday, the Antiplanner argued that urban form was rapidly changing -- that is, the suburbs were growing and central cities declining -- long before Congress created the Interstate Highway System, which was the first significant federal funding for urban roads. (Prior to 1956, almost all federal highway funding went to rural roads.) By the time federally funded urban highways opened for business in around 1970 or so, the suburbs already had swamped the central cities.

The case made by Mr. Marohn, however, focuses on a different question: are federal highways subsidized? "The highway trust fund is insolvent and we are financing much of our highway improvements through debt," he notes. Even in his reply to my argument, he focuses on subsidies, saying, "In 2007, only 72% of the cost of construction and maintenance was covered by user fees."

If the Antiplanner had known that subsidies, and not urban form, were the subject of the debate, I would have made a very different argument. First, I would have pointed out that the all the highways built from 1931 through about 1980 were funded almost 100 percent by gas taxes, tolls, and other user fees. It was only when Congress and the states began diverting those user fees to transit and other purposes that highway departments had to look for non-user-fee sources of revenue.

Second, I would have pointed out that subsidies to roads even today remain slight when measured on a per-passenger-mile basis. Some $33 billion in subsidies supported 4.57 trillion passenger miles in 2007, for a subsidy of just 0.7 cents per passenger mile. (I calculate the subsidies by subtracting the diversions from user fees -- $10.8 billion for transit and $11.7 billion for other purposes -- from the general funds going for highways -- $55.6 billion.) Considering that transit subsidies are roughly 100 times greater and are having much of an influence on urban form, I doubt anyone could say that two-thirds of a penny per passenger mile has done much to boost the suburbs.

Third, I would have pointed out that almost all of the subsidies are at the local level, not the federal or state levels. (From the same table, the feds spent $2.2 billion in general funds on roads but diverted $7.4 billion in user fees to non-roads; the states spent $17.9 billion in general funds on roads but diverted $14.1 billion of user fees to non-roads.) Non-existent federal subsidies can have no influence on urban form.

Fourth, the highway trust fund is insolvent only because Congress deliberately spent more than anticipated revenues so that it could fund its pork-fest on light rail, bridges to nowhere, and similar ridiculous projects. The fact that Congress is irresponsible has nothing to do with whether highways are subsidized or federal roads influenced urban form.

Opponents of the suburbs use claims of road subsidies to argue in favor of land-use regulation and transit subsidies. The Antiplanner says we should just get rid of all subsidies and let cities grow the way they want to grow.


This post, composed by Randal O'Toole, is jointly posted at the Antiplanner blog.