Although the title might seem busy at first, it's unlikely that Sinclair Lewis could have found a better way to express the tension that Carol Kennicott feels throughout this book. The tension we're talking about comes from the fact that Carol thinks Gopher Prairie—particularly Main Street, its center of excitement—is a total dump. "Main Street with its two-story brick shops, its story-and-a-half wooden residences, its muddy expanse from concrete walk to walk, its huddle of Fords and lumber-wagons, was too small to absorb her" (4.2.2).
If everyone in Gopher Prairie agreed with Carol and thought that the town and its Main Street were nowhere near good enough, there wouldn't be much of a conflict in this book; everyone would just pitch in and support Carol's plans to make the town better. But the problem is that when anyone other than Carol looks at Main Street, they see a bustling center of American pride and enterprise. When they look at this place, they truly see a "Main Street," a downtown hotspot that should fulfill every human need you could ever feel.
But that's just the thing: Carol looks at Main Street and can only think of a thousand other Main Streets across America that are exactly like it. The street is a symbol of the boredom and mediocrity to which she's committed herself by marrying Dr. Will Kennicott. Meanwhile, the rest of Gopher Prairie goes on thinking everything is awesome, thinking things like this: "But here she could put on her hat any evening, and in three minutes' walk be to the movies, and see lovely fellows in dress-suits and Bill Hart and everything!" (4.3.22). There's a big gap between these viewpoints, and Lewis suggests that this gap will probably never close.