Answer :

Gibbs
The migrants who lost their land and livelihoods to the Dust Bowl and headed to California were generally called Okies, Arkies, or Texies. These individuals faced great economic struggle due to the environmental problem and the overall economic impacts of the Great Depression. 
xiaoximu

Answer:

They were often referred to as "Okies" as most of the first migrants to arrive to California were from Oklahoma.

Explanation:

Not all migrants are from Oklahoma, however, most early migrants were and due to that, they were nicknamed Okies which was a neutral nickname turned to an insult by some people.