You do not have to do this alone. There are excellent resources available.
Online RN Number Databases. The FTC website has a searchable database. You can also use third-party sites that aggregate RN numbers. These are free and easy to use.
Vintage Fashion Forums. Communities like The Vintage Fashion Guild or Reddit’s r/vintagefashion are full of experts. Post a photo of your tag. People will help you date it within hours.
Social Media. Instagram and TikTok have huge vintage communities. Search for “Old Navy tag dating” or “vintage Old Navy.” You will find videos and posts that show real examples.
Your Own Collection. The best teacher is experience. Start a small collection of Old Navy pieces with known dates. Use them as reference points. Over time, you will develop an instinct for the tags.