The Truman Doctrine was an American foreign policy created to counter Soviet geopolitical expansion during the Cold War. It was first announced to Congress by President Harry S. Truman on March 12, 1947. More generally, the Truman Doctrine implied American support for other
nations threatened by Soviet communism. The Truman Doctrine became the
foundation of American foreign policy, and led, in 1949, to the
formation of NATO, a military alliance that is still in effect.
The New Deal<span> was the set of federal programs launched by President Franklin D. Roosevelt after taking office in 1933, in response to the calamity of the Great Depression, and lasting until American entry into the Second World War in 1942.</span>
You should look up Progressivism. Progressivists dealt with a lot of reforms in the early 1900s.
Alternatively, try looking up “US health bills since 1900.” If you need a starting point, look up the Pure Food and Drug Act/Meat Inspection Act (both in 1906) and Upton Sinclair’s “The Jungle,” which had a particularly large impact on meat inspection.
