According to Wikipedia, the Chicago metropolitan area has a population of about 10 million people, far less than Poland’s 38 million, which makes your claim completely impossible from the start. In fact, according to other articles, it seems that there are about 185 000 people of Polish descent living in Chicago (less than half a percent of the population of Poland), and a bit less than 10 million in the entire US (which is significant compared to the population of Poland, but still “only” about a quarter). And this article claims that there are “roughly 20 000 000 people of Polish ancestry living outside Poland” [in total], which is still less than the population of Poland.

It’s standard markdown afaik. Two new lines creates a new paragraphs, two spaces and one new line creates just a new line.