Answer:
It promised to transport Southern crops to markets in the North.
Step-by-step explanation:
The main reason why Southerners might have supported the American System was due to the promise that it would help transport Southern crops to the North. The American System was an economic plan that was mainly proposed by Congressman Henry Clay. The plan included tariffs to protect and promote American industry, the creation of a national bank and federal subsidies dedicated to infrastructure and agriculture.