OOC: We are assuming that the US is generally around the same size. Also no nuclear war or anything.
IC: The United States of America is not the first thing which comes to people's minds when it comes to being a prosperous country. While its literacy rate, GDP per capita and HDI are higher than other poorer nations when compared to most other countries it ranks pretty low in that regard.
But how can the US become a prosperous, first world nation?
It could use not having most of its banks not going bankrupt after their loans to the Entente nations became impossible to be paid back after WW1. Sure, that was something that hurt Germany quite a bit too, and arguably shattered Austria-Hungary after a hard-fought Phyrric victory, but it would be rather hard to say that it wasn't something that damage the US' economy quite a bit and in a way that not even the boost they got by selling weapons first and fighting Mexico later in WW2 could heal.
Then there's their problem with the Italian Mafia running a gargantuan submerged economy in the states that are the most prosperous (Rhode Island, Maryland, Pennsylvania and New York) and Neo-Knownothingers running the show in the Midwest and the Deep South. Neo-knownothingers in particular are indirectly responsible for why the USA's literacy rate is so low, since they fully committ to the idea that public schools are not for red-blooded Americans (meant to go to private schools) but only for foreginers that need to work to the bone for an unspecified amount of generations to become those aforementioned Americans.