First choose any US city by entering it and choosing it in the drop-down box. Then, name any US city in each 100 mile circle/ring as the rings expand outward from your city of choice, trying to name SECOND LARGEST city in each circle. The first circle will include your city of choice as a possible answer.
PLEASE NOTE - You must type a '.' (period) after each city to submit it to prevent answering another city with a name you would be have to type to get your answer. If multiple cities have the name you submitted, only the largest one will be counted.
You accumulate points based on the population of the city you named in relation to the second largest city in the circle. A smaller city’s point total will be the ratio of its population to the largest, so if you name a city of 75K people and the largest city has 100K, you get 75 points. Naming the largest city will get you points based on the ratio of the 2nd largest city's population to the largest city's.
When you run out of time or end the quiz, you will see the current ring’s 2nd largest city at right (under ‘Answer Stats’ by your coordinates).
For example, if you choose ‘Chicago’ – you will be shown a circle of radius 100 miles centered at Chicago. Naming any city in this circle (including Chicago) will cause another ‘ring’ of radius 100 miles to appear outside that circle, however - you will want to try naming the SECOND LARGEST city you can to get more points. After completing that circle, you now need to name any US city in the new ring (but not within any previous circles/rings), again trying to name the 2nd largest city. If there are not two cities within the next ring of that distance, the ring will keep expanding by that distance until two cities fall within it.
Quiz Takers 
This quiz proves that excluding CDPs from regular city quizzes in places like Maryland and Nevada essentially leaves those states almost completely empty.
Yeah but in some states even with CDP’s you don’t get all places – states like Alabama both cities/towns and CDP’s don’t cover the entire population of the state.
It comes down to the urbanization percentage of the state. In theory, if you add up all the cities and CDPs and divide the total by the state’s population, you should get a number close to that percentage.
The census data for Maryland does largely account for their urban populations. The thing that makes it stand out is the sheer percentage of its urban population that reside in CDPs (70%). The only other state that comes close to that percentage is Hawaii, which is of course 100% CDPs.
The Census Bureau states that CDPs are supposed to be “the statistical equivalents of incorporated places” as a way of generalizing the concept of city along the lines of “if it looks like a duck and quacks like a duck…”
I’m not saying it would be better if CDPs were included for every state. But if you’re going to include Hawaii’s, then you may as well include MD’s as well because the only practical difference between it and HI is that it also happens to have a handful of cities.
Nevada’s CDP percentage is also fairly high (40%), but if you were to include just the four huge CDPs in Clark county that have ~200K+ people (Paradise, Enterprise, Spring Valley and Sunrise Manor) then the statewide CDP percentage would drop to just 12%. But I guess you do count them in the Las Vegas metro quiz so it’s all good.
Since New England and New Jersey are almost entirely covered by municipalities covered in your city quizzes, shouldn’t their CDPs be excluded like Hawaii, since those places are already included in the town they’re in? I don’t think it makes sense for those places to show up in both types of quizzes.
I’m going to leave those ones, they are separate CDP’s and towns so the CDP’s are not technically included in my cities quizzes.
I am honestly surprised at the number of large CDPs in Maryland.
Certain metro areas seem to be heavy on the CDPs, too, namely Las Vegas, LA, the alluded-to Washington-Baltimore area and pretty much any metro area in Florida. Those are the keys to a good score, I think.