Many people urged america to fight the british to hold the northern boundary of oregon at:

36° 30'

49°

54° 40'

The correct answer is 54'40

"54'40 or fight" was the famous slogan adopted by advocates of fighting Britain for the Oregon territory during the middle of the 19th century. James Polk used this phrase and the support of the people to win the presidency. Ultimately, the US would not fight the British and they would come to a compromise on the 49th parallel, establishing the modern day border we have in Oregon.

the exclusive possession or control of the supply or trade in a commodity or service.

the roman empire began to fall