Before you are all set for your trip its better to gather all the information about the travel clinics and their locations. It might so happen your friend cannot find any travel clinic where he/she is and you have all the relevant information. Here are two professional medication organizations that provide directories of private travel clinics throughout the United States:

International Society of Travel Medicine (ISTM)
American Society of Tropical Medicine and Hygiene (ASTMH)
State Health Department Websites
Many state and local health departments throughout the United States provide travel immunizations. If they do not have travel clinics, they usually know who in the area provides vaccines for travelers. Please click on the state below to visit that state's local health department website. Note that the website itself may or may not provide travel medicine information.

Alabama
Alaska
Arizona
Arkansas
California
Colorado
Connecticut
Delaware
Florida
Georgia
Hawaii
Idaho
Illinois
Indiana
Iowa
Kansas
Kentucky
Louisiana
Maine
Maryland
Massachusetts
Michigan
Minnesota
Mississippi
Missouri
Montana
Nebraska
Nevada
New Hampshire
New Jersey
New Mexico
New York
North Carolina
North Dakota
Ohio
Oklahoma
Oregon
Pennsylvania
Rhode Island
South Carolina
South Dakota
Tennessee
Texas
Utah
Vermont
Virginia
Washington DC
Washington
West Virginia
Wisconsin
Wyoming 
Yellow Fever Vaccination Clinic Sources
If travel plans include visits to countries where yellow fever vaccination may be required for entry, find the nearest authorized U.S. yellow fever vaccine center here.