You must remember that your visa is valid only until its expiration date unless previously canceled. Therefore, if you have a valid U.S. visitor visa in an expired passport, you may use it along with a new valid passport for travel and admission to the U.S. Attempting to obtain a visa by the willful misrepresentation of a material fact, or fraud, may result in the permanent refusal of a visa or denial of entry into the U.S. If the consular officer should find it necessary to deny the issuance of a visitor visa, you may be allowed to apply again if there is new evidence to overcome the basis for the refusal. In the absence of new evidence, consular officers are not obliged to re-examine such cases.