RID Certification is generally accepted in all 50 states. This organization is an advocacy agency for the deaf community. NAD provides interpreter certification but testing dates and locations are determined locally in various areas. Check with the national office for testing contacts in your area. Be aware of the type of certification you need for the area in which you live.
Some states require certain types of certifications.
Some states will accept both RID and NAD certifications and some may not. Also, some states have local certifications that are acceptable in that state only. When preparing to work as an interpreter, contact your local deaf community agency or your local interpreter referral services. They should have current information about your state's requirements.