No, protons were not "invented" in the United States or any other specific country. Protons are fundamental particles that are a natural part of the universe. They have existed since the early moments of the universe and are one of the building blocks of matter.
The discovery of the proton as a constituent of the atom can be attributed to Ernest Rutherford, a British physicist, in the early 20th century. Rutherford conducted experiments in which he bombarded thin metal foils with alpha particles (helium nuclei) and observed the scattering patterns. Through his observations, Rutherford deduced the presence of a positively charged particle at the center of the atom, which he named the "proton" in 1919.
While scientific discoveries are often collaborative efforts involving researchers from various countries, it is important to recognize that protons themselves are a natural part of the universe and were not "invented" by any particular country or scientist.