Why could Spain not stop slaves from crossing the border into Florida?

He seventeenth amendment to the us constitution calls for the direct election of all us senators. this means that the people of each state get to vote to decide who will be their two us senators. before this, the legislatures of each state chose the two us senators from that state with no direct involvement of the average voter. why would this amendment be considered a reform? how would it benefit the people? even today some people claim that the seventeenth amendment was a bad idea. what arguments could be made for reverting selection of us senators back to the state legislatures?

What are new social classes emerged due to advancement in agriculture ?

What was one of the accomplishments of the space shuttle that what was one of the accomplishments the space shuttle that facilitated communication and entertainment ?