How did italian city-states like venice and florence become major banking and trade centers?

large families of powerful bankers established trade agreements with nearby cities. < -- alot of people say this

their location made them a natural route for travel between europe, africa, and asia. < some people say this

which is correct

no one really purchased it themselves, it was all america, they had debates etc.

confederacy: supported slavery, believed states should be able to nullify federal laws, supported low tariffs

union: everything else

the answer to your question is a because laws act as guidelines as to what is accepted in society. without it there would be conflicts between social groups and communities. it serves as a norm of conduct for citizens.