The Eastern Idaho Railroad (reporting mark EIRR) commenced on November 21, 1993, as a collection of two disconnected clusters of former Union Pacific (UP) branches.

Potatoes are a major commodity carried, using a unique loading technology to minimize damage during transit.

Operations are based out of the ex-UP depots at Twin Falls and Rupert.

The southern segment interchanges with UP at Minidoka, Idaho.

The Northern lines consist of: All lines connect for a total of 119 miles (192 km), served by four locomotives (August 2023), with operations based out of an office trailer on the north end of the Idaho Falls yard, the point at which EIRR interchanges with UP's Montana sub.