A series of major disasters occurred in the state from the 1920s to the 1940s. In 1928, a series of earthquakes destroyed many of the buildings in the capital. A much larger earthquake in 1931 was the largest in the state's history, devastating a number of cities along the coast. The 1930s brought the Great Depression, which along with the disasters, prompted wide-scale migration to Mexico City. In 1944, torrential rains caused massive flooding in the Tuxtepec region, causing hundreds of deaths. Oaxaca suffered more large earthquakes in 1980, 1999, 2017, and 2020, as well as one in 2018, which caused a deadly helicopter crash.