A biggie: the transcontinental railroad. Because it would economically improve wherever it was, both the North and the South competed for the railroad to be in their respective territory, evidenced by the Kansas-Nebraska Act and the Gadsen Purchase and induction of California as a free state in 1860.
In addition: people could get land cheap because it was abundant and might leave to start afresh economically.
There's other stuff I can't remember as clearly, but there's a little and I hope it helps :)
Answer:
Answer: Plains occur as lowlands along the bottoms of valleys or on the doorsteps of mountains, as coastal plains, and as plateaus or uplands. ... Plains may have been formed from flowing lava, deposited by water, ice, wind, or formed by erosion by these agents from hills and mountains.
