The U.S. Department of Health and Human Services (HHS) Substance Abuse and Mental Health Services Administration’s (SAMHSA) National Drug and Treatment Referral Routing Service (How’s that for a long name?!) provides a toll-free telephone number for alcohol and drug information/treatment referral assistance. The number is: 1-800-662-HELP. They also provide a searchable, online directory of alcohol and drug abuse programs located around the country. It is available here.
Substance abuse treatment facilities are licensed/certified by State governments. You can find the agency in your state responsible for these tasks by going here. These agencies often have online databases which list treatment programs by county.
For options outside of the U.S. try the database here