Susan Anthony and Elizabeth Stanton were responsible for starting the American Rights Association in 1866.

The missing word in the sentence: EQUAL

Susan Anthony and Elizabeth Stanton were responsible for starting the American Equal Rights Association in 1866.

The constitution of the American Equal Rights Association (AERA) stated the organization's purpose: "to secure Equal Rights to all American citizens, especially the right of suffrage, irrespective of race, color or sex." It was a group that grew out of the National Women's Rights Convention at the 11th such convention, held in New York in 1866.

Susan B. Anthony (1820-1906) Elizabeth Cady Stanton (1815-1902) were both key social reformers and activists in the women's suffrage movement.

the answer is American equal rights association