It runs for 100.1 miles (161.1 km), making it the system's longest line.

[4] Following the completion of track improvements the line opened to San Bernardino on March 4, 1996.

As of July 2016, eight trains in each direction serve the stations from San Bernardino - Downtown to Laguna Niguel/Mission Viejo on weekdays.

[6] The remainder of the trains servicing the IEOC Line cover more to all of the stations, except San Clemente Pier, which is only serviced on the weekends.

As of August 2016, the IEOC Line schedule has two trains on Saturday and two on Sunday, each servicing every station, including San Clemente Pier.