It's possible the definition has changed since your comment, but as of now, it says "at least 10%." I'd argue that, with the numbers above (which were before the last census and will have changed), Boston should qualify.
I think the main title is somewhat misleading as it could be taken to mean "the" most populous cities in each state, so I was surprised to see Nevada and Oklahoma with more than one, for example. I can see how that could be read the intended way, too. And the sub-title does make it clearer, but I didn't read that cause I thought the main title made sense.
"Cities with at least 10% of their state's population" would make it clearer.
I knew the one for South Dakota, saw the skyline in my mind, and typed Sioux City. I was surprised that it didn't work and even wondered if I should go back and try spelling it again but went on instead. Face palm.
How is Henderson up there when Las Vegas is not? That should be impossible considering that the population of Las Vegas is approximately eight times more.
Both are huge metro areas, in which the 'city proper' is much smaller. Also, both states include significant population centers that are not part of their biggest city.
100% of the DC population!!!
"Cities with at least 10% of their state's population" would make it clearer.
Regardless, nice quiz.
Wish there was a version for German states.