The United States generally has poor public transportation. In the 1930s and 1940s automobile companies worked hard to make cars and highways the dominant form of travel. They succeeded.
The Boston area, where I live, has relatively good public transportation. The system is complicated. It has a long history. An idiomatic way to saying this is that it is a "crazy quilt" or a "patchwork."
Public transportation is managed by the MBTA, the Massachusetts Bay Transportation Authority. It is often called "the T" because the symbol on bus stops and train stations is a T in a big circle.
Boston built the first subway in the US in 1898. Boston's subways are fairly good. In Boston you can get everywhere you need to go by walking and taking subways. The subways are a complicated tangle of four different systems: the Red Line, Green Line, Orange Line, and Blue Line. I am calling them subways, but they run partly underground, partly at street level, and partly on elevated rails.
The "commuter rail" system is a standard railway system with standard-gauge tracks, the same tracks used to travel between cities. It is relatively fast and comfortable. It is designed to serve people traveling to work. The schedule has many trains into Boston at the start of the work day, many trains out of Boston at the end of the work day, and not much at other times of day.
There is an extensive bus system that covers all the places not served by rail.
Compared to other cities, Boston's big airport is close to the city and well served by public transportation.
When we take the plane on vacation, we plan to walk to a train station, take the train into Boston, then take the "Silver Line" to the airport.