Where To Write
The first thing you need to do is decide which agency you are going to approach. If you are not certain about which agency has the information you are seeking, you should go to the library and check the descriptions of the various agencies in publications like the United States Government Organization Manual (US Government Printing Office), or call the local office of your representative in Congress.

Once you have narrowed down the possibilities, you might want to call the FOIA or the public affairs office of those agencies for more specific information.

If you think you know which agency has the records you are interested in, get the specific mailing address for its FOIA office. Any agency's FOIA office can be easily found. You can call the agency directly or look up the agency's FOIA regulation in a book called the Code of Federal Regulations (CFR) which you can find at any law library and many public libraries, or look them up on the Internet at: www.usdoj.gov/oip/foiacontacts.htm