How do you map a creature not proven to exist? It's not easy. It inevitably involves subjective judgments about which sightings, footprints, etc. are considered credible enough to include.
But this fellow has put an enormous amount of effort into the attempt, and I salute him for that. The sightings he includes reflect human population in many areas, notably Florida and the Northeast. The Pacific Northwest has, as you'd expect, a cluster of sightings that exceeds what you'd see if sightings were strictly a reflection of human population density or numbers.
This map shows one of the problems with Bigfoot in general. It is impossible - not unlikely, impossible - that a large unknown mammal exists in nearly every US state and Canadian province. A range covering most of North America, including the most populous areas, argues against the chance such a species exists at all: the odds of it going undiscovered are too great.
IF Bigfoot turns out to be real, I'd expect a cluster of up to a few hundred in the Northwest, possibly with some small relict populations as geographical outliers, reflecting a wider distribution thousands of years ago. Despite the number of sightings and the dedicated efforts of searchers, I'd be stunned if anyone ever turned up solid proof of such an animal in the Northeastern or Southeastern US.