Complex sentence: While the American cities prospered, the vast emigration from rural areas and continued neglect of the US agriculture industry created widespread financial despair among American farmers throughout the decade and would later be blamed as one of the key factors that led to the 1929 stock market crash.
Split into simpler sentences: While the American cities prospered, the vast emigration from rural areas continued to neglect the US agriculture industry, and created widespread financial despair among American farmers throughout the decade. This would later be blamed as one of the key factors that led to the 1929 stock market crash.