In the early 20th century, homesteaders converge on the southern Plains, where wet years, rising wheat prices and World War I produce a classic boom. Then, in 1931, a decade-long drought begins, exacerbated by the Great Depression. And just when it seems things could not get any worse, in 1935 the most catastrophic dust storm in history strikes on “Black Sunday.”In the early 20th century, homesteaders converge on the southern Plains, where wet years, rising wheat prices and World War I produce a classic boom. Then, in 1931, a decade-long drought begins, exacerbated by the Great Depression. And just when it seems things could not get any worse, in 1935 the most catastrophic dust storm in history strikes on “Black Sunday.”