Since the question came up in comments, a list of the biggest cities in the U.S. and Canada seemed in order.
It turns out to be a tricky question. For example, Seattle ranks as the 12th largest metropolitan area according to the U.S. Census Bureau's list of combined statistical areas. But that definition counts people based on commuting patterns and doesn't include places like Phoenix and Miami. Statistics Canada uses a different set of definitions. Then there's the case of San Diego, which has either 2,941,454 or 4,804,806 depending on whether Tijuana is included.
There are other complications. For example, the five-county Seattle area is 5,800 square miles while greater Houston is over 10,000. The city of Jacksonville (841 square miles) has about 200,000 more people than the city of Seattle (88 square miles). Unless otherwise mentioned, Cascadia Report generally conflates cities and metropolitan areas.
So, just for the record, here's the closest apples-to-apples comparison of the top U.S. metro areas (primary census statistical areas):
1. New York-Newark-Bridgeport -- 21,976,224
2. Los Angeles-Long Beach-Riverside -- 17,775,984
3. Chicago-Naperville-Michigan City -- 9,725,317
4. Washington-Baltimore-Northern Virginia -- 8,211,213
5. Boston-Worcester-Manchester -- 7,465,634
6. San Jose-San Francisco-Oakland -- 7,228,948
7. Philadelphia-Camden-Vineland -- 6,382,714
8. Dallas-Fort Worth -- 6,359,758
9. Houston-Baytown-Huntsville -- 5,641,077
10. Atlanta-Sandy Springs-Gainesville -- 5,478,667
11. Miami-Fort Lauderdale-Pompano Beach -- 5,463,857
12. Detroit-Warren-Flint -- 5,410,014
13. Phoenix-Mesa-Scottsdale -- 4,039,182
14. Seattle-Tacoma-Olympia -- 3,991,911
15. Minneapolis-St. Paul -- 3,502,891
Greater Vancouver clocks in at 2,170,976 and the Portland area at 2,137,565. Houston, Atlanta and Miami all passed Detroit in the last five years and Phoenix grew by more than 20%. For comparison, Toronto-Hamilton counted 5,555,912 and Greater Montreal 3,635,571
Here's a list, using a combination of counting methods, of largest population centers in the Americas.