The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA, /aɪsˈti/) is a United States federal law that posed a major change to transportation planning and policy, as the first U.S. federal legislation on the subject in the post-Interstate Highway System era.

The act was signed into law on December 18, 1991, by President George H. W. Bush and codified as Pub.

Section 1105 of the act also defines a number of High Priority Corridors, to be part of the National Highway System.

[11] There was not significant funding attached to these announcements: $30 million had been allocated to several states by 1997 to improve grade crossings,[12] but that was a very tiny amount in comparison to the billions required for a true high-speed network.

Aside from a few places in California and the Chicago–Detroit Line, most areas outside the Northeast Corridor continued to be limited to 79 mph (127 km/h) until $8 billion from the American Recovery and Reinvestment Act of 2009 was distributed in January 2010.