General Visa Information
The site http://travel.state.gov has information about obtaining a visa for those traveling to the United States. The site has links to websites for U.S. embassies and consulates worldwide. The embassy and consulate websites have very helpful information about procedures, timelines, communities served, required documentation, and fees.
Letters from ACM
Letters are issued from ACM headquarters for attendees to submit in support of their visa applications. Please send your request for a visa application letter to April Mosqus (firstname.lastname@example.org), and include your name, mailing address, and fax number, as well as the name of the conference you are attending. (Authors of papers/posters should include the title of their paper/posters.)