METRORail is the 22.7-mile (36.5 km) light rail system in Houston, Texas (USA). As of 2013, the METRORail has an average weekday ridership of 43,900 and total annual ridership of over 11.3 million. After Dallas' DART Light Rail, METRORail ranks as the second most-traveled light rail system in the Southern United States and the 12th most-traveled light rail system in the United States. METRORail is operated by the Metropolitan Transit Authority of Harris County (METRO).