Today we use the word for someone who travels. But how did the word come about? My friend had an interesting story. I checked it and it turned out to be true.
Here is the full definition, but for those in a hurry :
"Americans did not invent the suburbs, but they did create the commuter--someone who shuttles from a home in the suburbs to a job in the city and back again every day. Residing at a considerable distance from work was made possible by the invention of the railroad, and the name for someone who did so was made possible by the invention in the 1840s of a ticket good for multiple rides, the commutation ticket. Here commutation means "an exchange of one thing for another," especially if the new thing is a consolidation or reduction of the old. That is what the commutation ticket did: it exchanged individual tickets for a collective one at a lower price. The holder of such a ticket, being involved in the commutation, was thus called a commuter. Here is an 1865 exerpt from the Atlantic Monthly about railroads: "Two or three may be styled commuters' roads, running chiefly for the accommodation of city business-men with suburban residences."
In that statement we already see the modern connection of commuter with a lifestyle rather than a kind of ticket. Soon it no longer mattered whether the person held a commutation ticket, only where the person lived and worked. A commuter could ride a trolley, subway, cable car, or ferry as well as a train. In the twentieth century the commuter turned to the bus and automobile. "
now let me go and google metro and subway.