They were mainly agriculture based and slavery was free labor.
The answer would be the availability of new farming land in the west, while back east, most of their land had already been taken.
Gideon v Wainwright guaranteed that all defendants are entitled to an attorney, regardless of the severity of the charge. You can waive this right if you do wish, but all people can have one, either your own private lawyer, or a court-appointed one.
To permanently protect the people of the nation from unreasonable amendment proposals and ratifications