At first, the map will only display the Kanto region. During Generation III, after the player has ventured into the Sevii Islands, Celio will give them an upgraded map, featuring One, Two, and Three Islands. After defeating the Elite Four and getting the National Pokédex, Celio will upgrade the map to its complete extent, revealing the final four Sevii Islands. The map display can be changed among the four sections (mainland Kanto; One, Two, and Three Island; Four and Five Island and Navel Rock; and Six, Seven, and Birth Island) at will after getting each new map.
In FireRed and LeafGreen, certain locations have a guide (Japanese: ガイドguide) that details information on important places. This feature was expanded for every location on the Town Map starting in Pokémon Diamond and Pearl.
A new, separate Town Map was introduced in Sinnoh, and serves as a complimentary map application to the Pokétch. The Sinnoh Town Map offers flavor text descriptions of all visited locations in the game, and of all routes, visited or not. However, areas such as Fullmoon Island will not be shown unless the player goes there. It resembles a Nintendo DS.
Interestingly, Platinum's Town Map text data appears to have been taken directly from Diamond and Pearl: this is evidenced by Route 212's description including a reference to the house where shards can be traded for TMs. However, in Platinum, the TM-trading woman has been replaced by a Move Tutor.
"A map of the Kanto region! I hope she gives it to me..."
Before the release of Pokémon Gold and Silver, the only in-game source mentioning the name of the Kanto region was the Japanese-language text when examining the Town Map in Blue's house before the player obtains it.