California and Nevada both take a progressive view of drug possession cases. Instead of punishing defendants with prison and a conviction on their record, the courts offer "diversion" programs to rehabilitate the defendants. If successful, their cases are dismissed and they can petition to seal their records right away.
California's main programs that offer treatment instead of prison are PC 1000 and Proposition 36. PC 1000 lasts eighteen months and is open to people charged with simple possession or being under the influence. Prop 36 is similar except that it doesn't prevent you from having your license revoked.
Nevada's main drug diversion program for possession charges is Nevada Drug Court. Nevada drug court typically lasts a year and consists of weekly or biweekly drug counseling sessions and court appearances. Completing Nevada drug court usually relieves you from getting a conviction, and you can legally deny during job interviews that you've ever been charged.