Perhaps the most famous example of this in the Scriptures is in 2 Chronicles 7:14, spoken by the Lord to King Solomon after the building of the first temple in Jerusalem.
Starting in v. 13 for context, it reads, “When I shut up the heavens so that there is no rain, or command the locust to devour the land, or send pestilence among my people, if My people who are called by My name humble themselves, and pray and seek My face and turn from their wicked ways, then I will hear from heaven and will forgive their sin and heal their land.”
Now, we cannot make a direct application of this verse to the USA, since America is not chosen in the sense that Israel was chosen, and God does not call our entire nation “My people.”