Next, research the us population in 2015 on the internet. note the total population of the united states, and analyze the population pyramid’s shape. in a short essay, analyze the changes that have taken place to the us population between 1950 and 2015. based on your knowledge of us history, why do you think the us population changed as it did in that span of time? what effects do you think these changes have had on the physical environment of the united states? what do you think will occur between 2015 and 2070?