Tanning is the process by which uncured animal hides are made into leather. Tanning was the most important industry in the Catskills from the early 1820s until the Civil War, and its center was Kaaterskill Clove. Uncured hides were sent to the Clove tanneries, where they were treated with tannin, a chemical compound found in the local hemlock trees. Once the hides had been cured with tannin, they were then sent from the Clove to New York or Boston, where the leather was made into finished goods. Tannery owners created improved turnpike roads through the Clove to aid in the transportation of hides, thereby providing easy access to the mountains for traders, tourists and artists.