How did expanding the national territory increase sectional tensions in the united states? (5 points) northern and southern politicians disagreed as to whether congress had the authority to determine whether slavery would be allowed in new areas open to settlement. those living along borders often had greater social and economic connection to the neighboring countries. this complicated trade and land acquisition efforts. early national leaders promoted western settlement for agriculture, which matched southern interests, but northerners wanted to expand manufacturing. people moving westward to settle had little in common with people in the original states. they also had completely different political concerns, such as transportation.