Final answer:
Dorothea Dix's work benefited US society by advocating for and establishing state mental asylums, providing proper care and treatment for the mentally ill.
Step-by-step explanation:
Dorothea Dix's work benefited US society by advocating for and establishing state mental asylums. She exposed the deplorable conditions of jails and almshouses, where mentally ill individuals were mistreated and neglected, leading to public support for their improvement. Dix's efforts resulted in the creation of 32 mental hospitals in the United States and abroad, providing proper care and treatment for the mentally ill.