The first common carrier rail line in California was built between Sacramento and Folsom, in the foothills of the Sierra Nevada Mountains. It was eventually absorbed into the Southern Pacific.
Around the 1980s the eastern end of the line, between Nimbus and Folsom, was abandoned. The right-of-way was used to extend US 50 as a divided highway; the ROW was paved over by the new eastbound lanes. The abandonment in turn forced the closure of the SP branch to Placerville. This Placerville branch diverted from the SP line to Folsom near Natoma.
In the late 1980s, Sacramento began operation of its light rail line; the southern leg was built along the SP Folsom branch. Over the years the light rail line has extended further eastward. In 2004-2005, the extension to Folsom was approved, and the rails returned to Folsom. The eastern end of the light rail line runs parallel to the former right-of-way of the SP, since the light rail line was added after US 50 was widened.
Thanks to Mike Palmer for contributing information.
I believe that the writer may have meant to refer to the widening of Folsom Boulevard, rather than the current US 50 allignment, as the reason for the removal of the eastern end of this particular line. In fairness to the writer, Folsom Boulevard used to be the main highway prior to construction of the current freeway we all know as US 50. Kudos to you for helping others know the great, but all too forgotten history of Folsom and greater Sacramento.
The Placerville Branch has NEVER been abandoned
If you rely on the CA timetable from Altamont Press, note that in #19 it incorrectly shows the remaining "Placerville Industrial Lead" extending to milepost 13.7 near the Alder Creek trestle. Before light rail, track extended over the trestle and just past the freeway. During light rail construction (Folsom line opened in 2004) it was cut back to the east end of the Hazel Ave. light rail station (milepost 13.0). The wooden trestle at Alder Creek was replaced with a standard concrete bridge for light rail, but the stone abutments for the trestle were kept (non-functional) for "historic" reasons.
Light rail uses an original railroad bridge over Humbug Creek along Folsom Blvd between Blue Ravine and Parkshore. Can be viewed from a parallel bike trail.