U.S. crude oil production has risen sharply in recent years, with much of the increased output moving by rail. In 2008, U.S. Class I railroads originated 9,500 carloads of crude oil. In 2014, they originated 493,146 carloads, an increase of nearly 5,100% . However, rail volumes fell to 409,949 carloads in 2015 and to 211,986 carloads in 2016. Rail crude oil volumes are affected by a variety of factors, including pipeline capacity and crude oil price spreads.