I've been thinking a bit about the population figures for Mr Harry Turtledove's UNITED STATES OF ATLANTIS circa AD 2022 - specifically the number of residents in the five largest cities on the "Island Subcontinent" - and, having done a bit of mathematics based on the map at the other end of the link below (Identifying the Canadian provinces & US states comprising the territories shown, then totalling the population figures for the aforesaid after rounding them UP if above 500,000 and DOWN if below that figure) arrived at an approximate total of 139,000,000 Atlanteans in this year.
<The map in question>
Based on that figure, I then determined the percentage of total population (US) represented by the 5 most populous cities in the USA as we know it and then applied these percentages to determine the possible populations of their Atlantean equivalents: the problem with this method (and, by extension, the one used to arrive at the total Atlantean population) is that the American figures represent a population with a much larger continent from which to draw on and move around in (in fact arguably TWO whole continents, it being much easier to cross land borders than a body of water).
Geography may not be destiny, but it certainly shapes history, and the UNITED STATES OF ATLANTIS is shaped by a geography both subtly & blatantly different from our own.
Anyway, with that caveat, here are the Top 5 (Now I just need to decide which cities to assign these numbers to!):-
(1) 3,753,000
(2) 1,668,000
(3) 1,112,000
(4) 973,000
(5) 695,000
Comparing the Atlantean Top Five with their US equivalents, the Atlantean #1 (Hanover? Avalon?) is slightly behind Los Angeles but a whole million clear of Chicago (#3 USA as of AD 2022): #2 Atlantean (I really love the idea of Freetown being perennial runner-up, given it's tendency to come off second best in the novels but one suspects that city may have a hard time holding onto the "Number 2 with a bullet" slot by the dawn of the 20th century) is larger than Phoenix (US #5), but smaller than Houston (US #4).
The last Atlantean city to equal or surpass a US city in the Top Ten is #3 (which is larger than San Jose, but smaller than Dallas - putting it between US #9 & #10).
Atlantis as a whole outranks Mexico (#10 in the world:127,575,530) but is less populous than the Russian Federation (#9 in the world: 144,373,540).