British and Canadian but not Coloradan?

Solution 1:

Objectively, the inconsistency between rendering national proper names as adjectives (British and Canadian) and using a state proper name (Colorado) as is in the same syntactical position is difficult to justify. But in the United States, there is a very strong tendency to reserve use of the adjective form of a state name for situations specifically ivolving inhabitants of the state and to use the state name itself as the adjective form in most other situations.

So, for example, you have Kentuckian, North Carolinian, Texan, and New Yorker as noun and adjective forms referring to denizens of four states, but you have Kentucky barbecue, Carolina barbecue, Texas barbecue and—well, New York doesn't have a legitimate barbecue style of its own, as far as I know.

A "Colorado study" implies "a study conducted in Colorado and/or under the auspices of the Colorado state government," whereas (to me, at least) "a Coloradoan study" implies "a study conducted by or of citizens or inhabitants of Colorado." Consistent with this usage, New Yorkers could conduct a Colorado study if they did the research or published the results in Colorado, but they couldn't conduct a Coloradoan study unless the study focused entirely on subjects who were Coloradoans. Similarly, a "Texas gathering" refers in general parlance to a gathering in Texas, but a "Texan gathering"—unless explicitly defined otherwise—is likely to be understood to mean a gathering of Texans, in the state or outside it.

I don't know how this handling of state names as adjectives came about, but I would guess that it arose in part as a reaction to the large number of state names involved and to the awkwardness of coming up with appropriate adjective forms for each one ("Mainer"? "Delawarean"? "New Hampshireite"?) at the drop of a hat. The same goes for city names as adjectives: it is much simpler to refer in passing to "a Terre Haute specialty" or "a Kalamazoo restaurant" than to try to figure out a suitable adjective form of the proper noun.

In any event, I think that Atul Gawande and the editorial staff at The New Yorker handled all three adjectives sensibly and (judged in terms of normal U.S. usage) correctly.

Solution 2:

Exal's useful reference to Wikipedia gives us a big clue:

[Demonyms are] unofficial terms used to designate the citizens of specific states and the District of Columbia.

A demonyn refers to a citizen of the state, which is distinct from the report's origin in Colorado. Although the report might have been produced by one or more Coloradans, the report itself is not a citizen of the Rocky Mountain state.

Also, it's worth remembering that The New Yorker prides itself on editorial perfection, so much so that they are the only publication that can afford to poke fun at errors in other periodicals. Their copy editing and fact checking is profound and thorough. I'm not saying they never make mistakes, but you're not likely to find one.