If it helps demonstrate a lack of accuracy further. Their national archives have a rare map (the only full version of it with the other two existing in pieces in Cedar Falls and Waterloo) of Black Hawk County, Iowa in their collection cataloged under Ohio.
HOWEVER this is definitely not a situation of a Brit not having knowledge of the states in a different country (can you name all of the states/provinces in Canada, Mexico or Great Britain?)
The author is a New Yorker who contributes US stuff to them. The fact that eastern US urbanites have issues naming the 50 states and knowing there is a difference between them is a different thing all together.