What awsum is talking about is a "complete" kit that comes with an MSO, Manufacturer's Statement of Origin. With that, and usually some receipts for major components not included in the kit most states will put you through some tortureous paper shuffle, assign their own VIN, and then title it. If you buy just a chassis you won't get an MSO, so you'll most often need to save all the receipts for the components you buy, take it to some "official" inspection station for the state, and then get a VIN assigned. As suggested, the best route is to acquire a car already titled if possible.

Most states have a DMV web site, so you might check that for your state to get their specifics.