<P> Not all migrants traveled long distances; some simply went to the next town or county . So many families left their farms and were on the move that the proportion between migrants and residents was nearly equal in the Great Plains states . </P> <P> Historian James N. Gregory examined Census Bureau statistics and other records to learn more about the migrants . Based on a 1939 survey of occupation by the Bureau of Agricultural Economics of about 116,000 families who arrived in California in the 1930s, he learned that only 43 percent of southwesterners were doing farm work immediately before they migrated . Nearly one - third of all migrants were professional or white - collar workers . The poor economy displaced more than just farmers as refugees to California; many teachers, lawyers, and small business owners moved west with their families during this time . After the Great Depression ended, some moved back to their original states . Many others remained where they had resettled . About one - eighth of California's population is of Okie heritage . </P> <P> The greatly expanded participation of government in land management and soil conservation was an important outcome from the disaster . Different groups took many different approaches to responding to the disaster . To identify areas that needed attention, groups such as the Soil Conservation Service generated detailed soil maps and took photos of the land from the sky . To create shelterbelts to reduce soil erosion, groups such as the United States Forestry Service's Prairie States Forestry Project planted trees on private lands . Finally, groups like the Resettlement Administration, which later became the Farm Security Administration, encouraged small farm owners to resettle on other lands, if they lived in dryer parts of the Plains . </P> <P> During President Franklin D. Roosevelt's first 100 days in office in 1933, his administration quickly initiated programs to conserve soil and restore the ecological balance of the nation . Interior Secretary Harold L. Ickes established the Soil Erosion Service in August 1933 under Hugh Hammond Bennett . In 1935, it was transferred and reorganized under the Department of Agriculture and renamed the Soil Conservation Service . It is now known as the Natural Resources Conservation Service (NRCS). </P>

Which of the following was a human geographic factor that affected the dust bowl