A roadhouse is an inn-meets-bar known for seedy behavior. Why do we bring this up? Roadhouses are featured prominently in Carrie. And, as you might suspect, the roadhouses in this book serve as catch-all symbols for all-things-evil.
Just like breasts. And blood. Mr. King is really into writing about evil, didn't you know? And unfortunately for Carrie, though, there's no Patrick Swayze in her town's roadhouses. (Unlike in Dirty Dancing—do we really have to explain that joke to you?)
But we're getting off-topic. Margaret White, Carrie's zealous, god-fearing Momma, is fixated with roadhouses. Surprise, surprise. At one point, she says:
It comes at night. It will make you think of the evil that goes on in parking lots and roadhouses. (1.257)
Blech, Margaret is so vague sometimes. It's hard to tell what it is here. Evil? A man's penis? Both? In any case, she has good reason to be repelled by roadhouses. Her sinning (her word, not ours) parents owned a roadhouse when she was growing up: The Jolly Roadhouse.
Her dad was killed there in a barroom fight. That would leave a psychological scar on any girl.
That's not the only roadhouse in Carrie, though. There's also the Cavalier, the roadhouse where Chris and Billy Nolan met before the book began, which is "perhaps the very one where the doom of [Carrie's] creation had begun" (2.889). Huh?
See, Margaret's husband, Ralph, often went to the Cavalier to drink. And when he drank, he got randy. So Carrie may have just been conceived in the parking lot of the roadhouse where Carrie eventually kills Billy and Chris. Wild, right?
We mean, Margaret isn't wrong when says, "I know where [men] take you in their cars. City limits. Roadhouses. Whiskey" (1.711). We've been teenagers.
At the end of the book, Carrie burns down the Cavalier. We're not positive she knows Billy and Chris are in there at that point. But we do know that Carrie is turning into her mother; a self-righteous crazy-person who thinks it's her personal responsibility to vanquish sin in the world.
And taking out a roadhouse sure is a decent start.