The ports of Los Angeles and Long Beach tend to have a higher than average amount of air-borne particulates, due to all the ship, truck and rail traffic required to get thousands of containers per day on their way across America. As a result, little Pacific Harbor Line, which switches the port area, is always on the lookout for new, low-emmission locomotives. Testing on the PHL on July 15, 2016, is EMDX GP22ECO 7101, caught bringing a short train to an industrial section of Long Beach, California. Originally Penn Central GP40 3173 (built by EMD in October 1968), this engine became Conrail 3173 when that railroad was formed in 1976. CR sold it so KCS, as their 750, later renumbered to KCS 4750. It was later rebuilt as a "GP40-3" for Kansas City Southern, for which it wore number 4789 and, later, 2836.