People who own this book rave about the organization, the maps, the easy to understand explanations, and most of all the ability to look up not only where a county is, but WHEN it became a county. Many US counties were formed when a territory became a state, but almost as many were carved out of original counties. That’s how the Commonwealth of Kentucky wound up with 120 counties.
Just as important, every state has a different set-up as far as county/parish records. The Red Book tells you who keeps what records, not only state by state but county by county. Also, it has an extensive bibliography on background sources for even more detailed information on each state.
Keep it on your desk. Take it with you libraries, courthouses and on genealogy research trips.
And ask Santa Claus to put one in your stocking!