The developments and trends in American politics, economy, and society in the 20th century had global political significance. This century is characterized by enormous population growth and a strengthening awareness of a national American cultural identity. The USA experienced an economic boom that temporarily came to a halt during the Great Depression, but picked up speed again in the second half of the century. In foreign policy and military matters, the USA engaged in Latin America, Asia, and Europe. Domestically, they relied on a presidential democracy - with all its strengths and weaknesses.