Final answer:
The northern states were in favor of Hamilton's protective tariff because it promoted economic development, encouraged industrialization, and reduced foreign competition.
Step-by-step explanation:
The northern states were in favor of Hamilton's protective tariff for several reasons. First, a protective tariff would promote economic development by protecting domestic industries from foreign competition. This would allow American industries to grow and thrive, creating jobs and stimulating the economy. Second, the tariff would encourage industrialization, as it would make imported goods more expensive and therefore make American-made goods more competitive. Lastly, the tariff would reduce foreign competition, allowing American farmers and manufacturers to sell their goods in the domestic market without having to compete against cheaper foreign imports.