Interstate Exits Grew Their Own Settlements

An interchange in open country often carries a small cluster of businesses and nothing else. That cluster is a settlement form with its own rules of location.

Leaving a limited-access road is expensive in time

A driver on a high-speed road pays a real cost to exit, decelerate, transact and rejoin, and the cost is the same whether the stop lasts five minutes or forty.

Businesses therefore bundle at the interchange, because a driver who has already paid that cost will use several services at once.

The bundle is predictable: fuel, food, restrooms and lodging, which are the four things a long journey generates demand for and which cannot be delivered without stopping.

Spacing follows range rather than population

Clusters appear at intervals set by fuel range, driver endurance and the gaps between towns, so they can occur where almost nobody lives.

Where two long-distance routes cross, the catchment doubles and the cluster grows accordingly, sometimes to a size that resembles a small town.

Conversely, an interchange too close to a substantial town rarely develops one, because the town already supplies the same services.

Visibility from the road is the whole business

A driver decides at speed and usually with limited warning, so signage height and sight distance determine which business receives the traffic.

Tall pole signs exist for that reason alone, and sign height regulation is one of the sharpest local political disputes at interchanges.

Advance signage on the highway itself allocates attention as well, and inclusion on it can matter more to a business than its actual location.

The clusters serve travelers, not neighbors

Almost all customers are passing through, which means the businesses have no reason to serve local needs and local residents rarely use them.

Employment is drawn from surrounding towns, so the cluster imports workers daily while contributing little to the community they come from beyond wages.

Tax revenue can be substantial for the jurisdiction that contains the interchange, which produces persistent boundary arguments between neighboring townships and counties.

A route change ends the cluster completely

These settlements have no independent reason to exist, so a realignment, a new interchange a few miles away or a change in through traffic removes their entire market.

The same thing happened at an earlier scale when older highways were bypassed, and the abandoned motel strips along them are the previous generation of this form.

What survives longest is usually the fuel station, since it serves the residual local demand that the restaurants and motels never had.