"The Black Blizzard" April 14, 1935

On this date in 1935, the most notorious dust storm hit the Plains states. Known as "The Black Blizzard", huge clouds of dust stretched from the Plains of Texas north to the Dakotas. The fine dust was carried as far east as Washington, DC. The dust was created by a decade long drought and poor farming practices of the time period. The dry ground was picked up the strong winds and made airborne.
For more on the "Dust Bowl" days, visit this Wikipedia article.