Starting around 1955, and going up the 1985, how have changing
government policies and social programs affected the lives of American
Indians living in major cities (not on reservations)?

Interesting question!

In 1978 the Federal Government enacted the Indian Child Welfae Act.
One of the effects of the act was to give rights to all Indian
children placed up for Adoption off the Reservation to the Tribe. This
legislation was enacted to help stem the tide of the dying Native
American Culture, since so many young Native Americans were taken away
from their tribes in the previous centuries to be civilized. It also
effectively took away a Native American Woman under the age of 21's
rights to decide who would raise the child.

Read more here:
http://www.nicwa.org/