Giga Boost: Nation and World Edition

[Matti23]

Just trying to get a feel for how changing a few things would affect a nation.

Let's say that for some reason that in 2018 the USA has 1.4 billion people instead of roughly 320 million. Due to timeline shenanigans the infrastructure scaled to suit the alternate population as well as in OTL America. Let's call this alternate USA Giga America (not actually the name in the timeline).

I've heard that a populous nation introduces economies of scale that potentially enable a nation to become more prosperous. How big of a boost does this confer to the nation? How much would the GDP per capita be boosted with tax rates and demographics the same between both? Is doubling too much or perhaps an 80% boost too much? The natural resources are roughly the same.

As the title suggests i'm going to start changing things step by step in this world until it starts looking a bit wacky.

 

[Denv]

I'd say GDP per capita goes down. Same resources stretched over too many people. A nation with a higher population may probably be more wealthy because there's more people earning the same amount or more people earning a less amount so the grand total for the nation comes out higher.