The first and most important was the government created deficit spending. That's an import term to know -- especially now. It means that it spent more than it took in.
That spending created a larger debt than had seen before.
That spending created a trend that has been broken only once in the last century (Clinton's Administration).
The Federal Government became an employer. It paid for projects with deficit spending. (The government did worthwhile things with the Money it spent.
It created corporations, at least one of which it still owns TVA: Tennessee Valley Authority which provides electricity to Tennessee and some surrounding states.)