The north used the rising number of immigrants to .The south felt no need to employ immigrants on their plantations because

The north used the rising number of immigrants to staff the industrial economy (factory jobs, warehouse jobs, etc...) the south felt no need to employ immigrants on their plantations because the invention of the cotton mill had made slavery a more economical option.

Explanation:

a

explanation:

new evidence is discovered.

oversights and errors are corrected,

new technology is applied to evidence.