Final answer:
The race riots in the early 20th century were fueled by frustration and anger over discrimination, the perceived threat of African American success, and competition for jobs during the Great Migration.
Step-by-step explanation:
The race riots in the early decades of the 20th century had several underlying reasons. One of the main reasons was the frustration and anger felt by African Americans due to discrimination in areas such as housing, wages, job opportunities, and equal treatment by the police. Another reason was the perceived threat of African American success and increased social mobility, which led to a resurgence of white supremacist groups like the Ku Klux Klan. Additionally, the Great Migration of African Americans from the South to the North created tension and competition for jobs, which also contributed to the riots.