tons, of which Pennsylvania contributed 508,100 tons.

Michigan added 130,000 tons;13 Minnesota, of course,

produced none; but it was only a matter of time until

the vast deposits of Minnesota would be discovered and

mined.

 The Vermillion range came into production in

 1884, and the Mesabi, which was to become the most

 productive source of iron in the world, came into

 production in 1892.

 During the period 1854-1892, while the uses of

iron expanded so rapidly in the United States, all of

the major ore deposits of the Lake Superior region were

discovered and tapped. By 1969 they had yielded 3.9

billion tons,4 almost 18 billion cubic feet of pure

iron, or approximately 80 percent of all the iron mined

in the United States, the Mesabi alone contributing

over 2.7 billion tons of that total.

 The ore of the Mesabi remained rich for most

of that time, but increased demands of the wartime

economy of the 1940s, combined with domestic needs

during and prior to the war, exhausted the richest

ores. By the 1940s many of Minnesota's mines had been

closed and the mining towns abandoned, and Michigan iron

mines were growing deeper.


 13Manufactures of the U.S. in 1860, p. clxxvii.

 14Minerals Yearbook, 1969, p. 576.