In Amy's youth she moved to Sitka to attend the Sheldon Jackson College, and then moved to Petersburg, Alaska. During the 1920s in Petersburg, Amy married Norwegian-born Casper Hallingstad Sr. (1901-1980) and they later raised six children together.
During the early 1930s, as Amy's children began to attend school in Petersburg, Amy became angry that the Native children in Petersburg were forced to attend a segregated school. Since Alaska Natives had to pay taxes that went toward the public school system, Amy was able to force the closure of the Native school in Petersburg and soon Alaska Native children were able to attend the public school in Petersburg. Her oldest son, Casper Hallingstad, Jr. was the first Alaska Native student in the Petersburg public school. During this time Amy became very active in the Alaska Native Sisterhood (ANS), serving in various leadership roles within the Petersburg ANS Camp 16, and later serving as Grand President from 1947-49 and 1953-56. She was a supporter of the land claims movement as early as 1937. Amy was also instrumental in forming the Petersburg Indian Association in 1948.
During this time Amy also made it a practice to forcibly remove signs from businesses in Southeast Alaska that contained discriminatory language, such as "No Natives Allowed." Amy was also an organizer of boycotts against businesses that discriminated against Alaska Natives, or preferred to hire non-Natives. Newspaper articles speak of her efforts of enforcing a boycott of the Petersburg movie theater, which had segregated seating. The boycott continued until the segregated seating practice was eliminated.
As Grand President of ANS she also made strong efforts to pressure businesses, such as canneries that sought to employ non-Natives, to change their policies and hire locally. She influenced reforms that were enacted at canneries in Hood Bay, Excursion Inlet, Pillar Bay, and Chatham. She fought to improve medical care to Alaska Natives. She also regularly corresponded and met with state politicians about the important political issues of the day. With her contemporary, the celebrated Elizabeth Peratrovich, they both worked towards ensuring Human Rights were guaranteed to Alaska Natives. Amy was an advocate for Native rights until her death at age 72 in 1973.