If you are a citizen of the USA and do not bring a passport, you can enter the Dominican Republic by:
Copied from
http://dr1.com/travel/English/Tips.html#anchor15409: Citizens of the United States may enter with passport or with an original birth certificate and additional photo-bearing official document (such as voter's registration or driver's license.) Minor's may enter with only an original birth certificate. Cuban residents of the United States may enter with their U.S. residency card and additional official photo-bearing document.
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Jim Hinsch JimHinsch@CSI.COM