The United States railroad system consists of a vast network of operations that includes over 780 railroads with more than 230,000 employees and 200,000 miles of track in operation. The freight railroad industry is dominated by the seven largest freight railroads, referred to as Class I railroads, which collectively operate over 1.7 trillion ton-miles and accounted for more than 90 percent of annual railroad-freight revenues in 2012. There are also 10 Class II freight railroads that typically operate over 350 to 900 miles per railroad, and about 750 smaller Class III freight railroads with less than 350 miles of track that typically perform point to point service over short distances. In addition, Amtrak and 29 commuter railroads collectively carry an average of about 670 million passengers a year over 23 billion miles.