The sights along a state highway in Grapevine, Tex., could hardly be distinguished from any other highway near a major American city, with Audi, Jaguar-Land Rover and Infiniti dealers on one side and other upscale rivals on the other. A short drive away are a couple of local places: a sports complex called Drive Nation and the Bear Creek Golf Club, a public complex with two championship golf courses.

What distinguishes these businesses is that all pay rent to the nearby Dallas-Fort Worth International Airport, the nation’s fourth busiest, serving over 65 million passengers a year.

Like Dallas-Fort Worth, airports all over the country are looking for new ways to cover their costs, as they seek more income for terminal and other improvements. That means the fees and rents paid by parking lots, rental car companies, taxis and the businesses under their roofs are also increasingly important as airports try to hold the line on, or even lower, the fees paid by airlines.

If an airport can reduce airlines’ fees, it can keep carriers that might otherwise switch to another city, said Henry Harteveldt, a travel industry analyst and president of the Atmosphere Research Group, as well as appeal to budget carriers that prefer low costs and even persuade carriers to enter new markets by making it more economical. The lower the fees, Mr. Harteveldt added, “the more likely it is an airline can offer lower fares to passengers.”