Final answer:
Dorothea Lynde Dix conducted an investigation of jails and almshouses in Massachusetts and worked to publicize the inhumane conditions in which mentally ill individuals were being kept. Her efforts led to the establishment of state mental hospitals.
Step-by-step explanation:
Dorothea Lynde Dix was instrumental in improving the conditions for the mentally ill. She conducted an investigation of jails and almshouses in Massachusetts and found that mentally ill individuals were being kept in inhumane conditions, such as filthy cells and being chained, beaten, and lashed. Dix worked to publicize these conditions and gained public support for their improvement. Her efforts led to the creation of state mental hospitals, with a total of thirty-two being founded in the United States and abroad over the next thirty years.