Answer:
A. The Missouri Compromise caused a great political crisis between the North and the South due to the belief of each region that they had rights to determine the fate of slavery for their specific region. This ultimately resulted in the balance of power being upset and ultimately led to the Civil War in 1861.
B. The American System was a major contributor to the period of the Era of Good Feeling. The system called for strong government, states' rights, promotion of agriculture and industry, a protective tariff, a national bank, and internal improvements. This period also saw the nation improve diplomatic relations with Europe with the Rush-Bagot Agreement of 1817 which established an official border between the US and British Canada. The American System provided a stable economic and political platform which created an atmosphere of relative prosperity and unity in the United States.