The information provided here is primarily for those looking to research the current state of both industries, though it can be used to start historical research. If you are interested in looking historically see the History page and specifically the Market Research section of this guide.
The U.S. government has used various code systems for industry research to classify business entities by activity. Knowing these codes can make some areas of research easier because some databases, many print sources, and the U.S. government (most notably the Census) use them in their indexing, charts, graphs, lists, and indexes. The system now used by the Census Bureau is the North American Industrial Classification System (NAICS) and both restaurants and lodging are part of Major Group 72 Accommodation and Food Services.