The correct answer to this open question is the following.
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The Homestead Act of 1862 provided land to willing settlers in an effort to continue the settlement of the west. As settlers improved and adapted to their environment this eventually led to the following "The ground became unstable and unable to support the new farming structures."
On May 20, 1862, US President Abraham Lincoln signed the Homestead Act, which gave Americans 160 acres of land if they were committed to pay a registration fee and live there to work the land and make it productive.
The problem was that by the 1930s, the soil was affected due to farming activities and the "dust bowl." A drought that stroke the southern plains. The dusty winds and the dry weather killed domestic animals and crops failed. It became impossible to farm the land and farmers decided to move from that place.