U. S. Cattle Industry in the Nineteenth Century • Wild cattle multiplied for centuries in the Southwest.
• Growing cities created more demand for beef.
• Cowboys rounded up cattle and drove them to shipping centers
on railroad lines.
• The introduction of barbed wire and windmills led to large
fenced ranches.
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d. The need to process large amounts of cattle made meatpacking a major industry.

Explanation:

Meatpacking developed rapidly in the 1800s due to factors such a huge supply gained from the multiplication of cattle over centuries and a demand to match coming from the growing cities on the Eastern seaboard.

Coupled with the growth of the railroad and the refrigerated rail trucks being made available, the demand for meat increased as it was more accessible.

This demand led to a need to process much more cattle and led to the meatpacking industry becoming a major one.