iBrary Guy has a fairly recent post comparing and contrasting
GovTrack.us and LegiScan. Yes, one can track federal and state legislation using a commercial service but both of these offer a basic level of tracking legislation for free. GovTrack.us is for tracking federal legislation and LegiScan for state. The post provides some background information, how to use, and what results may be expected.
These are useful resources if you don't have access to a subscription database but want to follow federal and state legislation.
Ernster, the Virtual Library Cat