When Americans think about U.S. leadership in the world, they often think of military power, famous presidents, or economic achievement. But they might 
be less likely to name an area in which the United States has led the world for decades: science.
From lifesaving vaccines for devastating diseases like smallpox and polio, to novel materials like semiconductors and superconductors, to robotic rovers that can explore Mars, science has made possible discoveries that revolutionized the world, and much of it started right here in the United States.