According to the copyright office circular 22* there are three main ways to investigate the copyright status of a work:
1. Look at the work (or a copy) for copyright notice, author, publisher, and place and date of publication. (To see an example look at the backside of the page with the title of most books.)
2. Use Copyright Offices sources. (Virtual Card Catalog)
3. Request the Copyright Office search for you. (Information on the Records research and Certification Services)
*United States Copyright Office, Circular 22: How to Investigate the Copyright Status of a Work (last reviewed 2/2013). (This circular gives instructions on the second and third type of investigation.)
"To be copyrightable, a work must qualify as an original work of authorship, meaning that it must have been created independently and contain a sufficient amount of creativity." Circular 33: Works Not Protected by Copyright 1 (last revised 9/2017).
Circular 33 notes that ideas, methods, and systems cannot be copyrighted. Example given:
"Paulina Neumann submits an application to register a recipe for caesar salad dressing. In the “Author Created” field, Neumann asserts a claim in “text.” The work consists of a list of eleven ingredients with the following instructions: “(1) puree anchovies, garlic, Dijon, egg yolks; (2) drizzle oil in gradually to emulsify; (3) add lemon, parmesan cheese, salt, pepper, Worcestershire and tabasco sauce.” The Office will refuse registration for this work, because the list of ingredients is uncopyrightable, and the instructional text contains an insufficient amount of creative authorship." p. 2
In addition names, titles. short phrases, typeface, font, lettering, layout and design, blank forms, and familiar symbols and designs cannot be copyrighted.
From the Copyright Offices's FAQ's:
"How do I protect my sighting of Elvis?
Copyright law does not protect sightings. However, copyright law will protect your photo (or other depiction) of your sighting of Elvis."