Answer:
The reason behind the expansion was to expand the presence of American settlers in the West.
Step-by-step explanation:
The motive behind the expansion into Texas and Oregon was the Manifest destiny. The Manifest Destiny introduced by the government for the territorial expansion in the West to the Pacific. The main goal was to spread its white American settlers in the westward region. Americans drove towards westward to get access to land across the entire North American continent.
Maine had a different reason for its establishment for the settlers. The first European settlement in the area happened in 1604 by French, and English settlers began to come in the 1620s. Settles came to Maine to start a new life from Europe.