From what I gather, drug sentences start out relatively friendly to the offender and escalate quickly with repeat offenses and increased amounts. A first time offender with a personal amount of drugs will almost certainly not do any jail time beyond the night he spends in jail on the initial arrest. He will have the option of going through a drug program / drug court, if that exists in his state. Repeat offenses, or aggravated offenses (involving a gun, for example) combined with large amounts of drugs can get you up to a mandatory life sentence, which is pretty draconian. Certainly not as bad as southeast Asia, though, where 15 grams of heroin is a capital offense.