Final answer:
The main nineteenth-century social reform movements in the US were the abolitionist, women’s rights, and mental health reform movements.
Step-by-step explanation:
The three main social reform movements of the nineteenth century in the United States were the abolitionist movement, the women’s rights movement, and the mental health reform movement. While the labor reform movement was also significant, it is not typically classified among the three main movements of that era. The abolitionist and women's rights movements were particularly intertwined, with many reformers advocating for both causes. Progress in these movements was driven by a shared desire for freedom, emancipation, and expanded rights for marginalized groups in America. Notable figures like William Lloyd Garrison and Frederick Douglass were key in advancing the abolitionist cause, while the women's rights movement saw great advances through the organized efforts that grew out of abolitionist organizations.