Source and then specific question and answer.
How can the States charge tolls on Interstates I paid taxes to build?
The Interstate System is free of tolls for the most part, but tolls are collected on some segments. Most major toll roads were planned or built before the Congress authorized significant amounts of Federal funding for the Interstate highway program. These segments were built by toll authorities created by State or local legislation to issue bonds as a way of financing construction. Toll revenue is used to retire bonds and cover operating and maintenance expenses.
One of the controversial issues Congress considered before passing this legislation was what to do with the turnpikes that had been built or planned in Interstate corridors without Federal funding. In an extensive congressional debate, members considered purchasing the bonds to allow removal of the tolls, but this option would have cost hundreds of millions of dollars without creating any new Interstate mileage. Another option was consideredóconstructing toll-free Interstate highways in these corridorsóbut it would have diverted funds needed for new highways in areas not served by Interstate-type facilities. It also would have jeopardized the legitimate right of the toll authorities to pay their bondholders. Therefore, Congress decided to include some toll facilities in the Interstate System to ensure connectivity.
Federal law has changed over the years to allow turnpikes on the Interstate System under other circumstances. In all, the 46,876-mile Interstate System includes approximately 2,900 miles of turnpikes.