The correct answer is behavioral confirmation. This is
considered to be a type of self-fulfilling prophecy by which people’s social
expectations are likely to lead them to behave in a way that causes other
people to confirm the expectations that they expect.
Cascade Tunnel, the longest railroad tunnel in the United States, located in central Washington about 60 miles (100 km) east of Seattle.
Any area that the US would have gained from winning the Mexican-American war
Wagon train should be the answer :)