What is "riverside-rialto"

Riverside-Rialto was a line operated by the Pacific Electric Railway from 1914 to 1940, running from Downtown Los Angeles to Downtown Riverside. This was the longest line in the Pacific Electric, and the only line to have exclusive trackage owned by the Union Pacific instead of the Southern Pacific Railroad. The line reached its highest ridership the year it opened, but never recovered at a time when the Inland Empire was far less populated and a commute of that distance was rare.