When America began as a nation of thirteen states, the "frontier" was the land between the states and what other boundary?

pacific ocean

Explanation:

Lewis and Clark went all the way to the pacific ocean

managing the colonial war effort while also forcing for and moving towards america's independence was the major agenda of the debate in course at the second continental congress. the delegates at the congress also adopted the united states declaration of independence, in so doing acting as the ''de facto'' national government of what later became the united states of america

i would say b probably