Climate types on the west coast of North America and the influence of North American mountains on climate.

1. From south to north, the western North America has polar climate, temperate continental climate, temperate maritime climate and Mediterranean climate. The long and narrow distribution is due to the influence of topography. There are tall Rocky Mountains on the west coast of North America, which run north and south, blocking the water vapor in the ocean and making the climate long and narrow. 2. According to the push-pull theory of population migration, the United States has developed economy, many employment opportunities, good living conditions, perfect infrastructure and many pulling factors. In addition, Mexico has a large population, relatively backward economy, and difficult employment, resulting in thrust factors. The combined action of thrust and tension led to the migration of Mexican population to the United States.