The people who founded the United States knew that innovation and invention would be a major key to economic growth. It was for this reason that they specified in the Constitution that inventors should be able to have exclusive rights to their inventions for a period of time.
Since then, the US economy (and thereby the standard of living of its people) has been driven by innovation and invention. For example, the invention of the steamboat made much more commerce possible in the early US. Innovations in the railroad industry did likewise later on. These innovations in the railroad industry were made possible in part by the invention of the telegraph.
Later on, more inventions and innovations helped increase the American standard of living. One can point to everything from Henry Ford's use of the assembly line to the creation of the personal computer. These inventions and millions of others have contributed to give Americans a high standard of living.