This stamp was issued to celebrate the opening of the first portion of the Arkansas River to commercial navigation. The system has 17 locks and dams. Twelve of these are located in Arkansas and five in Oklahoma. In 1971, an Act of Congress designated the official name of the waterway as the McClellan-Kerr Arkansas River Navigation System. This name is commonly abbreviated as MKARNS. The MKARNS system is made up of 445 river miles with a minimum water depth of nine feet. Its benefits include: water supply, navigation, fish and wildlife conservation, recreation, hydroelectric generation, and flood control. Over the past 30 years, the MKARNS has created 54,000 jobs, generating a payroll of over $1 billion.