LC periodically updates these guidelines and problematic headings. Subject Headings for more information. You should consult the individual description of each field when assigning LC-based subject headings. See the OCLC Authority File if you need an additional reference. Treat the word States as a general subdivision.
Chronological subdivisions qualify a subject in terms of time.
You may use dates as a subdivision for this purpose. However, if you use dates to identify a specific occurrence of an event and do not qualify the subject in terms of time, treat the subdivision as a general subdivision instead. 10 United States. Civil War, 1861-1865. Treat subdivisions that qualify a subject in terms of the time in which items were written as general subdivisions.