I can only speak from an IT perspective. I arrived in PM after following the career path through operator, programmer, Analyst, team leading etc.
I don't think this is necessarily the best way but it does mean you have a great deal of knowledge about what people in your team are likely to be up to.
Essentially, I think you need a skill, like your economics ,and then look for opportunities where you can lead people on activities and gradually move into PM, ie by stealth.
There are plenty of things to learn in PM but it is essentially a peoples role, so if you are good with people so much the better.
If you are set on this as a career, I suggest you work with your existing company to find a way in. For example bring it up at your next review as an area you are interested in moving to. You already have some skills, eg I guess project appraisal. Maybe they will pay for your training. As you probably know training is very expensive if you have to pay for it yourself.
Also do some reading.
Anything about people, teams, motivation etc. Negotiation skills. Contract law.
Look up your own Project Management Institute in USA. There are local chapters which you could join and get help from. There is a qualification you can try the PMP. It is all on their website.
If you are really feeling masochistic try the UK Prince2 Web sites just type "PRINCE2" into your favourite search engine. PMP and Prince 2 are trying to do the same thing in different ways. Prince2 is far more process bound and looks clumsey. But as a UK qualified Prince2 practitioner I can say once you come to understand it and work within it, it is a great help.
Finally forget about MS Project until you understand what PM is about. Some people think that because they know the ins and out of the software, that they are good PMs. In my experience they are deluded.
There is a massive amount of info on the web.This is just my view.