Main Street, U.S.A. is the first "themed land" inside the entrance of the many Magic Kingdom-style parks run by The Walt Disney Company around the world. Based on Walt Disney's hometown of Marceline, Missouri, Main Street, U.S.A. is designed to resemble the center of a turn-of-the-century (early 1900s) American town. At Tokyo Disneyland, this area is named World Bazaar.

Walt Disney said, "For those of us who remember the carefree time it recreates, Main Street will bring back happy memories. For younger visitors, it is an adventure in turning back the calendar to the days of grandfather's youth." Above the firehouse at Disneyland is Walt Disney's personal apartment, fully furnished but off-limits to the public. A lamp is kept burning in the front window as a tribute to his memory.

Each Main Street, U.S.A. features tracks for a horse-drawn trolley which runs along its length, except at Tokyo Disneyland and Hong Kong Disneyland. The shops are laid out in a fashion to take advantage of the fact that people tend to walk on the right side of the street: along the right of the street (as a guest enters the park) are shops selling cameras and film, hats, and other items more likely to be purchased by someone starting his day at the park; along the other side of the street are shops selling toys and souvenirs and other items more likely to be purchased before departing. Main Street, U.S.A. is also home to City Hall, in which the Guest Relations office is located.

The buildings along Main Street, U.S.A. use forced perspective to appear taller than they really are. The false second stories of all the buildings are slightly smaller than the first stories, a few feet short of full size, and the third stories are even smaller than the second. If the original Disneyland architects had made the buildings a full two stories high, they would have looked incongruously tall compared to the castle in view at the end of the street.

The names painted in the windows on Main Street serve as credits for some of the many people, Imagineers and others, who contributed in some way to the creation of Disneyland. Largely they appear as fictional businesses (gyms, realtors, dentists and the like), and they often refer to a hobby or interest that the person in question had. Ub Iwerks's window, for example, refers to his prowess with cameras. For Disneyland's 50th anniversary, on July 17, 2005, a first-story window on each Main Street was unveiled with a dedication to all the cast members (employees) who had worked for Disney throughout the years.