Political maps are maps that show the boundaries—also called borders—of countries, states and counties. Borders can change over time for different reasons. For example, when one country takes over another, the border of the first country expands to include the second. A country can also trade, buy or sell land to another country and gain new territories after a war. When borders change, political maps change, too. The map of the US that we’re used to seeing didn’t always look this way. It has changed many times since the year 1776, as borders changed and grew, and as we created new states. Which of these events most likely changed the borders of political maps of the US?

A
the US buying Alaska from Russia in 1867

B
a large earthquake hitting California in 1906

C
2.6 million Americans losing their jobs in 2008

D
many immigrants coming to New York City in the in the late 1800s