Announcement. As from the editions for the year 1958 the Abridged Nautical Almanac and the American Nautical Almanac will become identical in content, and will be reproduced from identical material, apart from the title pages and covers; they will for the time being retain their present titles, and will continue to be printed and published separately in the United Kingdom and the United States. The unified Almanac will be produced jointly by H.M. Nautical Almanac Office of the Royal Greenwich Observatory, Herstmonceux, and the Nautical Almanac Office of the U.S. Naval Observatory in Washington, to meet the general requirements for surface navigation in the two countries.

Unification became a possibility with the decision to prepare copy for the Abridged Nautical Almanac on the card-controlled typewriter in H.M. Nautical Almanac Office; this machine is identical with that at the U.S. Naval Observatory, which has been used to prepare copy for the American Nautical Almanac since 1950. A large number of arrangements were tried for the daily pages, some with one day to the page or two days to the opening, and others with three days to the opening. The consensus of opinion in the United Kingdom favoured the latter form, which is already in use in the American Nautical Almanac. This opened the way to a detailed investigation into an arrangement that would prove acceptable to users and producers in both countries. The unified Almanac is the result of this collaboration.