What states is workers compensation mandatory?

Could you please clarify which specific context or country you're referring to when asking about the mandatory nature of workers' compensation in certain states? In the United States, for instance, workers' compensation insurance is generally required by law for most employers to cover medical expenses and lost wages of employees who are injured or become ill due to work-related causes. However, the specifics can vary from state to state, so it's essential to consult the relevant state laws and regulations to understand the mandatory requirements in a particular jurisdiction. Could you elaborate on your question or provide more context so I can provide a more accurate answer?