OTL's calculation is a messy iterative thing
https://en.wikipedia.org/wiki/Unite...apportionment#The_method_of_equal_proportions
Why are you using '620', when OTL it's 435 for the House, and has been (barring temporary increases when new states were added between censuses) for some considerable time?
Also, that is a very odd list of new states. Puerto Rico is obvious; Cuba, unlikely but believable; why Nova Scotia and no other Canadian Province, that's weird; Bermuda and US VI are so small they'd break the US state system, Bahamas is small enough it would strain it (see below)
Where is DC? Why is that not a state, if these others are?
Look at
https://en.wikipedia.org/wiki/List_of_U.S._states_and_territories_by_population
Puerto Rico would slot between CT and IA
Nova Scotia at 942,926 (2015) would be between Delaware and Montana (thus likely giving it the same 1 seat as those)
Cuba at 11.27 million (2013) would be between Ohio and Georgia
Bermuda at 65,024 (2013); US VI at 65,024 (2010) would break the US State system; and the Bahamas at 392,718 (2016 est.) would strain it.
OTL, there are complaints that Wyoming has almost twice the representation per citizen as Montana does, due to Wyoming's small size and Montana being rather bigger, but still with only one seat.
you are proposing 2 micro states that 8 times worse.
My suggestion would be a 'non-state state' (Basically make a Constitutional amendment that gives all US citizens living in US territory the right to representation - which currently doesn't exist, of course. So, Guam, US VI, the Marianas and Samoa, and in this case Bermuda and the Bahamas, would have their votes aggregated and counted as if they were a state. Whether DC would be part of this or its own weirdity, is debatable either way.
Or, create 3 grab bags - an Atlantic/Eastern one (Bermuda, Bahamas, US VI, PEI if it were included); a Pacific/Western one (Guam, Marianas, Samoa); and DC (Central one).
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Getting Cuba into the US as a state (or two) rather suggests a Spanish-American War PoD, and if so, then the populations are going to be WAY different. Firstly, due to butterflies, secondly, if Cuba's rich enough to be a viable US state, it's probably going to have had slower population growth. Just as one example.