US writer Margaret Lee Runbeck once wrote, "Happiness is not a station you arrive at, but a manner of traveling." But traveling is not always happy, at least for the two people in the movie Green Book.

The movie was based on the true story of a road trip through the southern US in the early 1960s. In the film, the black pianist Don Shirley hires Italian-American Tony Vallelonga to drive him to perform, but they face problems because of Shirley's skin color. These problems lead them to form a special friendship.

"There's something so deeply right about this movie, so true to the time," wrote US film critic Mick LaSalle at the San Francisco Chronicle. The time LaSalle talked about was between the late 1870s and 1960s, a very different period in US history, when many parts of the country had Jim Crow laws, which allowed racial separation （种族隔离）. These laws made life and travel dangerous for African-Americans. They couldn't use certain hotels, restaurants, or even gas stations. They had to be indoors after sunset or they might go to jail. Even famous black people had to follow the laws.

But in 1936, a black mail carrier named Victor H. Green had an idea. He made a list of friendly businesses in New York City. He published the list as a small book with a green cover. The Green Book helped African-Americans travel more safely. Then, in 1964, Jim Crow laws went away. The book went away, too. Today many US people still remember the time of Jim Crow, but they probably don't know about the Green Book. Thanks to this movie, maybe people can remember it again.