That would halve my manpower.
Plus, I haven't had nearly the same amount of mass death OTL Russia had experiences up to this point (excluding the Great War). There was no Russian Civil War, no purges, no famines, no mass executions by the Communists. Despite what everyone thinks of Russia, I've been surprisingly peaceful and stable. Meanwhile, the Americas have had numerous wars, England's been fighting one war or another pretty much non stop for the past 2 decades, Germany and the French states had the Rhine-Rhone War, the various Burgundian fiascos, the Arabian War, etc, etc, etc. I still don't understand how the UK has been fighting the Fireworks War for almost a decade now, losing more people in the process than they did in the Great War, and hasn't lost so much as a stability point. Hell, the same party's been in charge the whole and keeps getting reelected!
That brings us to the Great War, where my casualties were 2-4 times higher than the RL Great War. But that holds true for everyone, so theoretically, that should have effected everyone's manpower pool equally. At the end of the war, Poland was two to three years away from having
zero manpower (which annoys me when they cause so much trouble because there can't be that many Poles left). Since then, I've had a booming economy, a stable domestic environment (for Russia) and no major wars. These are all prime factors for a population boom, as experienced in RL in the 1920s. Plus, during this TL's Great Depression, my economy
increased, not decreased, further fueling a large population. Therefore, based on the vast territories I hold, the classic factors for a population boom present, and the warfare and poverty present in the Western Hemisphere, I don't think it's entirely unreasonable for my manpower pool to be on roughly the same level as the Americas combined.