Living in Boulder county, Colorado, I've often heard humorous references to "Chief Niwot's curse" by fellow transplants, and a few not-so-humorous references by native Coloradans. I've heard a lot of vague formulations of the curse, and got curious about it. It seems vague formulations are what you find on the Web as well. Apocrypha get no respect.
The neatest reference I find is in the Boulder Weekly's "A-to-Z Guide to Boulder: How to talk like a native"
Niwot's Curse—When white men first came to Boulder in 1858, they were looking for gold. What they found instead were Southern Arapaho warriors under Chief Niwot who wanted them to leave. When they refused, Chief Niwot supposedly uttered this curse: "People seeing the beauty of this valley will want to stay, and their staying will be the undoing of its beauty."
That page also has a very brief summary of Chief Niwot's story, which is very interesting, and worth pursuing in primary sources. Overall the page is a reasonable guide to "Boulder weird", which is tolerable to my taste in medium quantities (I love hanging out in Boulder proper, but I'm glad I live one US 36 exit and one big hill south. Not so glad, I admit, about living among the little boxes made of ticky-tacky).
For me, Boulder valley was just part of the magic in the curse. It was in 1995 when I took a road trip with friends from Fort Collins to San Francisco, driving through Boulder as tourists and then on through Golden (striking in a somewhat more industrial way) and onto I-70 through the jaw-dropping rockies. While in Fort Collins, we also trekked up famous Highway 14 to the continental divide. I've been all over the U.S. and I must say three of the four most gorgeous passes I've ever seen are in Colorado. Yosemite is the one out of four, and I think Independence pass edges it out.
I don't know whether it was specifically Boulder valley and the Flatirons that did for me--it was more likely Fort Collins and environs--but Niwot's curse took a hold, and I found myself determined to move to Colorado to settle, succeeding in 1998 when we moved to Fort Collins.
Calabar, Cairo (Egypt), Birmingham (England), New York, Cleveland, Gainesville, Enugu, Owerri, Yola, Port Harcourt, East Brunswick, Cleveland, Milwaukee, Chicago, Dallas, Peoria, Fort Collins, and now Superior/Boulder. I'd never lived anywhere in my life a full three years before settling here in Superior (I'll have lived six years here in May). Lori does love Colorado, but I think she loves even more that my moving itch seems to have subsided. To most of those under its hold, the famous curse has the devious trick of looking like the most extravagant sort of blessing.