Yes. Drugs, at least the illegal ones, can/do/will land you in jail and eventually prison. Marijuana possession alone is enough, depending on how much you have and/or how it is packages (ie "with intent to distribute"). This depends on which state you are in, whether you are caught while crossing a state line (air travel) and the colour of the uniform on the officer who catches you (federal v. state). Some states have decriminalized possession but the US fed has not.

As a general rule, US "jails" house people awaiting trial and/or serving short sentences. "Prisons" house people with more than one year to serve. Prisons are generally much nicer places than jails.

(I went to a US law school, spent lots of time dealing with low-level offenders all of which were drug related. It's a horrible horrible system.)