which was the last country to challenge the United Sates' control of Oregon?

http://history.state.gov/milestones/1830-1860/oregon-territory

The last country to challenge the United States' control of Oregon was Great Britain. To confirm this information, you can follow these steps:

1. Begin by searching for "Oregon boundary dispute" or "Oregon boundary question" in a search engine. This will give you specific results related to the historical dispute over Oregon's territorial boundaries.

2. Look for reliable sources such as historical records, books, or recognized websites that focus on American history or territorial disputes.

3. Explore the search results and select sources that provide information on the Oregon boundary dispute between the United States and Great Britain.

4. Read through the selected sources and look for information about the final challenges to the United States' control of Oregon. This should confirm that Great Britain was the last country to challenge the United States' control of Oregon.

By following these steps, you should be able to find reliable information to answer the question about the last country to challenge the United States' control of Oregon.