This map shows the western expansion of the united states. describe events that explain the border differences between these maps. use information from the maps and the lesson in your response. use complete sentences. besides land, what did the united states gain from expansion? use information from the maps and the lesson in your response. use complete sentences.

1. The event that explains these border differences was the Mexican American war of the 1800s. During this war, America gained many new lands and established California as an American Territory

2. Not only did the United States gain land but also many valuable resources during these expansions. Some of these resources included gold oil and coal.

doesn't make any since

explanation:

the name of the theory is landmass theory.