Why were mines and lumberyards no longer in demand during the great depression

Because miners and lumberjackers are producers of goods that are used in the production process, not of consumer goods, generally speaking, and During the Great Depression, these kind of goods (also known as capital goods) had a much sharper fall in demand than consumer goods, even when consumer goods also experienced a great fall in demand.

In more general terms, the Great Depression represented such a massive economic contraction that demand for labor in any economic sector fell by a lot. This is why U.S. unemployment hit its highest levels in history during these years.

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