I have a 2000 Lincoln Navigator and lately it has been making this squeaky noise when I drive slow and seems to be getting worse.I am unable to take it to be fixed right now so I just wanted to see if maybe someone knows what it might be.The noise I'm not sure what side it is coming from but it sounds like its around the tire area.

The decision to not get this diagnosed now could cost you more if you continue to drive your vehicle.
Take your truck in for a complimentary brake inspection.
Most brake shops will inspect your brakes for free. Plus, most shops have someone who's competent enough to inspect your suspension at the same time. If you tell them that you're hearing noises, they can help diagnose this. Make sure you're aware of any potential diagnosis charges before they proceeded.

Yes.. I agree with CaptainRich, brakes sometimes come with sensors the rub up against your rotors that will squeak when your brake linings are getting wore down. It's there to tell you that you better get your brakes serviced!!

This squeaky sound doesn't really sound like the sound of brakes going bad.It sounds more like if you were to bounce up and down in your car that noise that it makes except this noise is constant and louder.My truck also leans more to one side not sure if this has anything to do with the noise.

Struts normally need replacing around 90,000 miles. Look into Monroe Quick Struts, with a lifetime warranty.