Choose two of the changes you noticed between the 1965 and 2015 population pyramids for Germany. Use your knowledge of history and the country to explain why the changes likely occurred.

The population pyramids show that the US population more than doubled in the years between 1950 and 2015 from 150 million to 320 million. Also, the demographic makeup of the population changed. In 1950, young people made up a large percentage of the population and became known as the baby boom generation. This term refers to the increase in people born just after World War II in the United States. In 2015, the population is more evenly divided between ages and genders, although there is a growth in the amount of older Americans, which once again shows the effects of the baby boomers.

The drastic increase in the overall US population undoubtedly has had an impact on the US physical environment. A population that has doubled means that cities and towns have also probably doubled in size on average. Urban sprawl and pollution has become a more serious problem between 1950 and 2015. It doesn't seem that the population could double again between 2015 and 2070, but the US population will likely continue to grow, resulting in more potential pollution and environmental problems in the United States.

The two biggest changes in the population pyramids of Germany in the periods of 1965 and 2015 are that in 1965 the population pyramid is well structured by age, while in 2015 the pyramid is increasing in size in its upper parts but becoming thinner in the lower parts.

In 1965 we have the ''baby boom'' period, where the birthrates went up, so there was a big percentage of young population. The population pyramid was wider at the bottom because of the high birthrates, slowly decreasing in the middle sections, and becoming smaller and smaller towards the upper parts.

In 2015 though, the population pyramid looks much different, with the middle section being the biggest, the lower part much thinner, and the upper part is also bigger. This is due to few reasons, like the shift from rural to urban population, pursuing of careers of the youngsters, being too expensive in the cities to rise more kids, and all of that contributed to a significant drop in the birthrates in the country. But also, it is worth mentioning, that the lifespan has increasing, so the population is aging and it is becoming older and older.