Naming

PR-66 is, in reality, an extension of older expressway PR-26, as both expressways are attached (that is, there is no need to take an exit to enter the other expressway, much like PR-18 and PR-52). PR-66 was assigned that number after U.S. Route 66 in the United States.^{[citation needed]}

Controversy

PR-66 is very close to the El Yunque National Forest and at the start of construction there were problems between developers and environmental activists. Several acts of disobedience took place, including removing beams which had already been installed.^[7] The expressway was planned to be extended to Fajardo but due to the close presence of the forest reserve, it was accorded to be extended to Río Grande and connect to PR-3 which has several exits between that municipality and Fajardo. It is possible PR-3 will be converted into a complete freeway, in that segment, as it approaches PR-53.^[8][9]

The short expressway is very expensive in terms of toll fees and many people still go through PR-3 as a consequence. There are no plans to change the cost. The current toll fees are $1.50 and $1.00, respectively. This makes this small freeway the second most expensive tollway in the US (excluding bridges and tunnels), after the Dulles Greenway in Virginia in terms of its small length, about 30 cents per mile (19 ¢/km). The result is that PR-66 has low traffic most all the time, including during rush hours.^[10] As of December 2011, the toll must be paid by pre-paid AutoExpreso.^[11]