The first America's hospital of the kind was opened in the latter half of the 18th century, though by 1751 some hospitals had already set apart wards for the mentally ill in order to separate them from other patients. It was necessary as the insane often acted in an aggressive manner, thus, being dangerous.

Nevertheless, the first institution for the "persons of disordered minds" was incorporated only in 1768 while its first patients were admitted 5 years later.

It is an interesting fact that for hundreds of years all mentally ill people were considered lunatics.