One of King's high school classes was Fantasy and Science Fiction, and one of the novels he taught was Dracula. King was surprised at how vital it had remained over the years; the kids liked it, and he liked it, too. One night over supper King wondered aloud what would happen if Dracula came back in the twentieth century, to America. In the following days, King's mind kept returning to the idea. "He'd probably be run over by a Yellow Cab on Park Avenue and killed, if the legendary Count came to New York, that was." But if he were to show up in a sleepy little country town, what then? King decided to find out, and wrote 'Salem's Lot, which was originally titled Second Coming.

Stephen King's second book, 'Salem's Lot (1975)--about the slow takeover of an insular hamlet called Jerusalem's Lot by a vampire patterned after Bram Stoker's Dracula--has two elements that he also uses to good effect in later novels: a small American town, usually in Maine, where people are disconnected from each other, quietly nursing their potential for evil; and a mixed bag of rational, goodhearted people, including a writer, who band together to fight that evil.
Simply taken as a contemporary vampire novel, 'Salem's Lot is great fun to read, and has been very influential in the horror genre. But it's also a sly piece of social commentary.
As King said in 1983, "In 'Salem's Lot, the thing that really scared me was not vampires, but the town in the daytime, the town that was empty, knowing that there were things in closets, that there were people tucked under beds, under the concrete pilings of all those trailers. And all the time I was writing that, the Watergate hearings were pouring out of the TV.... Howard Baker kept asking, 'What I want to know is, what did you know and when did you know it?' That line haunts me, it stays in my mind.... During that time I was thinking about secrets, things that have been hidden and were being dragged out into the light."
Sounds quite a bit like the idea behind his 1998 novel of a Maine hamlet haunted by unsightly secrets, Bag of Bones.

While teaching a high school Fantasy and Science Fiction course at Hampden Academy, King was inspired by Dracula, one of the books covered in the class. "One night over supper I wondered aloud what would happen if Dracula came back in the twentieth century, to America. 'He'd probably be run over by a Yellow Cab on Park Avenue and killed,' my wife said. That closed the discussion, but in the following days, my mind kept returning to the idea. It occurred to me that my wife was probably right — if the legendary Count came to New York, that was. But if he were to show up in a sleepy little country town, what then? I decided I wanted to find out, so I wrote 'Salem's Lot, which was originally titled Second Coming".

King expands on this thought in his essay for Adeline Magazine "On Becoming a Brand Name" (Feb 1980): "I began to turn the idea over in my mind, and it began to coalesce into a possible novel. I thought it would make a good one, if I could create a fictional town with enough prosaic reality about it to offset the comic-book menace of a bunch of vampires."

Political influences of the time were very heavy on King's writing of the tale. Corruption in the government was a significant factor in the inspiration of the story. "I wrote 'Salem's Lot during the period when the Ervin committee was sitting. That was also the period when we first learned of the Ellsberg break-in, the White House tapes, the shadowy, ominous connection between the CIA and Gordon Liddy, the news of enemies' lists, of tax audits on antiwar protestors and other fearful intelligence. During the spring, summer and fall of 1973, it seemed that the Federal Government had been involved in so much subterfuge and so many covert operations that, like the bodies of the faceless wetbacks that Juan Corona was convicted of slaughtering in California, the horror would never end . . . Every novel is to some extent an indavertant psychological portrait of the novelist, and I think that the unspeakable obscenity in 'Salem's Lot has to do with my own disillusionment and consequent fear for the future. The secret room in 'Salem's Lot is paranoia, the prevailing spirit of those years. It is a book about vampires, it is also a book about all those silent houses, all those drawn shades, all the people who are no longer what they seem. In a way, it is more closely related to Invasion of the Body Snatchers than it is to Dracula. The fear behind 'Salem's Lot seems to be that the Government has invaded everybody."

King first wrote of Jerusalem's Lot in a short story of the same title, penned in college (but published years later for the first time in the anthology collection Night Shift).

In his non-fiction book, Danse Macabre, King recalls a dream he had when he was eight years old. In the dream, he saw the body of a hanged man dangling from the arm of a scaffold on a hill. "The corpse bore a sign: ROBERT BURNS. But when the wind caused the corpse to turn in the air, I saw that it was my face - rotted and picked by birds, but obviously mine. And then the corpse opened its eyes and looked at me. I woke up screaming, sure that a dead face would be leaning over me in the dark. Sixteen years later, I was able to use the dream as one of the central images in my novel 'Salem's Lot. I just changed the name of the corpse to Hubie Marsten."

In a 1969 installment of "The Garbage Truck", a column King wrote for the University of Maine at Orono's campus newspaper, King forshadowed the coming of 'Salem's Lot by writing: "In the early 1800s a whole sect of Shakers, a rather strange, religious persuasion at best, disappeared from their village (Jeremiah's Lot) in Vermont. The town remains uninhabited to this day."

In addition to Dracula, Shirley Jackson's The Haunting of Hill House and Grace Metalious' Peyton Place are often cited as inspirations for 'Salem's Lot.