Is it illegal to ride a bike on the sidewalk in the US?

Hello there, I'm curious about something related to laws in the United States. I've heard some differing opinions on whether or not it's illegal to ride a bike on the sidewalk. Could you please clarify if this is a nationwide rule, or does it vary from state to state? And if it's generally legal, are there any specific circumstances where it would be considered illegal? Thank you for your help in clearing this up!