The Schuylkill River (/ˈskuːlkɪl/ SKOOL-kil, locally /ˈskuːkəl/ SKOO-kəl) is a river running northwest to southeast in eastern Pennsylvania. The river was improved by navigations into the Schuylkill Canal, and several of its tributaries drain major parts of Pennsylvania's Coal Region. It flows for 135 miles (217 km) from Pottsville to Philadelphia, where it joins the Delaware River as one of its largest tributaries. Millions of tons of anthracite coal from Pennsylvania's Coal Region flowed by waterway and rail into Philadelphia to feed the iron and steel industry.