Question

what helped define the border between the united states and british - controlled canada? the adams - onis treaty the convention of 1818 the admission of mississippi as a state the american democratic experiment

Explanation:

• The Adams-Onis Treaty settled U.S.-Spanish borders, not U.S.-Canada.
• The Convention of 1818 established the U.S.-British Canada border along the 49th parallel for much of its length.
• Mississippi's state admission was unrelated to international border definition.
• The American Democratic Experiment refers to U.S. governance, not border agreements.

Answer:

the Convention of 1818