In the game, players play are ACME agents and travel to 51 locations around the United States (one for each state and the District of Columbia) in order to find Carmen Sandiego's V.I.L.E. henchmen. At the first rank, gumshoe, the player has 6 days (144 hours) to track down, identify, issue a warrant for, and capture the criminal. Every third or fourth crime a player solves, he goes up in rank. This means that the player will have to travel through another city in the same amount of time. There are ten different ranks, and the player will run into Carmen at the rank of Master Detective after he has solved 38 crimes.
Source: Wikipedia, "Where in the USA is Carmen Sandiego", available under the CC-BY-SA License.