The image shows the US/British border dispute in the 1860s and early 1870s.

Question

Which is the best interpretation of the US/British boundary dispute shown on the map?

The subject of the boundary dispute was Vancouver Island.
The San Juan Islands became part of British North America in 1872.
The San Juan Islands became part of Washington Territory in 1872.
The dispute was settled when Vancouver Island gave up the San Juan Islands.

Answer 1

The best interpretation of the US/British boundary dispute shown on the map is that the San Juan Islands became part of Washington Territory in 1872.

This is because, after a series of negotiations and the eventual arbitration by Kaiser Wilhelm I of Germany, the San Juan Islands were awarded to the United States, thus becoming part of Washington Territory. The other options are not accurate in the context of the dispute historically.