The leather, however, is to be regarded rather as a novelty than as a permanent addition to the industry. American tanners, too, have been quick to learn the methods of making the best of the foreign varieties of leather, and in some cases they have even improved on the original processes. Among these leathers of foreign origin are russia, a strong and pliant variety, generally of a red or black color, and with a peculiarly penetrating odor due to the oil of birch; and Cordovan, a small-grained, soft leather, which takes its name from the Spanish city of Cordova. It was from the gradual modification and improvement of this last that the so-termed morocco leather has resulted. This, with its brilliant colors and beautiful finish, has come to be very widely used. The manufacture of it is carried on in nearly all places where the leather industry flourishes at all, but the centers of the business are at Philadelphia, Pa., Newark, N. J., Wilmington, Del., and Lynn, Mass.
The distribution of the tanneries in this country, and as a result the centers of the leather trade, has been largely determined by the distribution of tanning materials. Tannin, the active vegetable principle of tanning, has been found in a wide variety of plants and trees. As a matter of fact, however, the only substances used largely here are the bark of the oak, the hemlock, and the sumach. Hemlock bark is found generally north of central Pennsylvania, throughout northern New York, north of Lake Michigan, and through Maine and Canada. Oak bark, on the other hand, is found abundantly in the vicinity of the Cumberland and Alleghany Mountains, and the lesser ranges of the Blue Ridge, while the sumach flourishes in Virginia and Maryland. Southern sumach, however, is not so highly esteemed as that obtained from Sicily, and much of this is imported. Some other varieties of tanning materials also are imported, like terra japonica, but the staff of the tanner in this country is the oak and hemlock. It is in those sections of the country that the tanneries are found. New York is the largest general leather market in the United States, while Boston stands close to it, especially in upper leather. Philadelphia, Cincinnati, Chicago, and Baltimore, too, are leading trade centers. The growth of the industry has been very marked since 1830. In 1850 the total product of leather in the United States was valued at $32,861,796, and the capital invested was estimated at $18,900,557. New York State stood at the head of the list, with an output valued at $9,804,000; while Pennsylvania came next, with $5,275,492; and Massachusetts third, with $3,519,123. In 1880 the value of the output had increased to $113,348,336, and the capital invested to $50,222,034. There were then 3,105 tanneries in the country. The position of the six leading States is well represented by this table: