Washington D.C. - The U.S. and Mexico reached a liberal air treaty that would clear the way for airlines on both sides of the border to set their own prices and fly any routes they choose between the two nations with unlimited frequency.

The treaty, signed Friday by Transportation ministers from the two countries after two years of negotiations, still must be ratified by the Mexican senate. Officials from both nations said that if implemented it would increase traffic and enhance competition, benefitting fliers.

The accord "lays the groundwork to take advantage to the maximum of the boom in the airline industry happening in both countries," said Gerardo Ruiz Esparza, Mexico's transportation and communications minister. The treaty encourages code-sharing among U.S. and Mexican carriers and would boost the overall number of fliers between the nations, Mr. Ruiz Esparza said.

Thomas Engle, U.S. State Department deputy assistant secretary for transportation affairs, said the agreement eliminates rules that limited service to just two or three airlines from each country on about 30 cross-border routes. The enhanced competition "should help keep fares affordable," Mr. Engle said.

Mexico was one of the largest countries with which the U.S. lacked a modernized air accord. Others include Russia and China. The U.S. currently has 118 so-called "Open Skies" air treaties with foreign governments. Although U.S. officials said the Mexico accord doesn't follow that model, they said it removes all the barriers in the current, restrictive U.S.-Mexico agreement.