Marijuana is a fairly short-term drug. It is only going to decrease your ability to drive for about three hours, which may not even be as long as a night of drinking alcohol would. Typically, experts agree that the effects wear off in an hour or two. In some specific cases, minor effects can linger for a day, but it's not as if you are experiencing the full impact of the drug for 24 hours.
Do not make the mistake of thinking that no one can find out you used marijuana after one to three hours, however. Even if the effects wear off, it can still show up in your system.