The frontier ceased to exist because settlers claimed more than 11 million acres of former Indian land and most of the frontier was now settled.
The meaning of the term founders is someone who starts something. The dictionary definition is:
a person who establishes an institution or settlement.
There is more meanings to it but this is the main one.
Answer:
What changed could be that a two-party system was established for our elections, we no longer go by the articles of confederation and instead go by the constitution, and what stayed the same I would say would be the right to free speech and assembly