Western Hemisphere Traveler Improvement Act of 2007

Western Hemisphere Traveler Improvement Act of 2007 - Amends the Intelligence Reform and Terrorism Prevention Act of 2004 to require as part of the certifications required prior to implementation of the western hemisphere travel initiative (Initiative), that: (1) a pilot program of at least one state has been initiated and evaluated to determine if an enhanced driver's license valid only for citizenship verification for U.S. entry from Canada meets documentation requirements; (2) a study has determined the number of passports and passport cards that will be required to be issued; and (3) sufficient passport adjudication personnel have been hired.

Authorizes a person under 16 years old who is a U.S. or Canadian citizen to enter the United States with a birth certificate if the person: (1) is accompanied by the individual's legal guardian; and (2) is entering the United States from Canada or Mexico.

Authorizes a person under 18 years old to enter the United States with a birth certificate if the person is traveling under adult supervision with a public or private school group, religious group, social or cultural organization, or a youth sports team.

Directs the Secretary of State and the Secretary of Homeland Security to establish a state driver's license and identity card enrollment program to permit a U.S. citizen with a qualifying driver's license or identity card or a Canadian citizen with a qualifying comparable document to enter the United States from Canada by land or sea without providing other citizenship documentation. Authorizes program expansion to include other countries.

Directs the Secretary of Homeland Security to accept a birth certificate as proof of citizenship for any U.S. citizen who is traveling from one part of a state to a noncontiguous part of that state through Canada if: (1) the citizen cannot travel by land to such part of the state without traveling through Canada; and (2) the travel in Canada is limited to no more than two hours.

Directs the Secretary of State, during the two-year period beginning on the date on which the Secretary of Homeland Security publishes a final rule in the Federal Register to carry out the Initiative, to: (1) provide one facility in each of at least six designated cites or ports of entry in which a passport or passport card may be procured without an execution fee; and (2) develop at least six mobile teams along the U.S. northern and southern borders to issue passports or other identity documents without an execution fee.

Requires the Secretary of Homeland Security to do a cost-benefit analysis of the Initiative prior to publishing such final rule.

States that Congress' intent in enacting section 546 of the Department of Homeland Security Appropriations Act, 2007 was to prevent the Secretary of Homeland Security from implementing the Initiative before the earlier of June 1, 2009, or the date on which the Secretary certifies to Congress that an alternative travel document (passport card) has been developed and widely distributed to eligible U.S. citizens.

Amends the State Department Basic Authorities Act of 1956 to extend passport processing authorities for civil service and foreign service annuitants.