I'm guessing Alaska and Hawaii were omitted not because of their location, but because of the timeline on this map. Alaska was purchased from Russia in 1867, and then the gold rush hit in 1897. Alaska didn't become a U.S. state until January 3, 1959.
Here's a group of Tlingit men and boys in Auk Village, Juneau - 1887.
Also, here's a picture titled "Auk Indians & Cabins" Juneau, 1887
Hawaii also became a state in 1959 on August 21. In 1887, Hawaii was converting over from a monarchy to a democracy because of the influence of their own monarchy interacting with people from foreign lands. That was the year that they enacted the "Constitution of the Kingdom of Hawaii" also known as the "Bayonet Constitution".