The Illinois State Toll Highway Authority (ISTHA) is an administrative agency of the State of Illinois, United States. The roads, as well as the Authority itself, are sometimes referred to as the Illinois Tollway. The system opened in 1958 in the Chicago area, and has subsequently expanded to include the eastern and central sections of Interstate 88 (I-88) extending into the northwestern part of the state. Beginning in 2005, the system was reconstructed to include more lanes and open tolling. Open tolling uses I-Pass transponders to collect revenue as vehicles pass antennas at toll plazas or designated entrance or exit ramps. As of 2016, ISTHA maintains and operates 292 miles (470 km) of tollways in 13 counties in Northern Illinois.