look under Find a Car and they show the reports that dealers have already

If you are looking for the history of a specific vehicle - than there are no free sites. Nobody is going to collect all that data, pay for all the computers to run the site and all the employees to run the computers - and give it away for free.

Sellers can buy a vehicle history report and share it with you!
On cars.com, on AutoTrader.com and on many other sites you will find dealers who have run Carfax reports are providing thousands of reports "free to you." Many dealers also provide these on their own web sites.

Also you can visit carfax.com and look under Find a Car and they show the reports that dealers have already paid for.

There is an NICB service which reports on total car loss only - pretty limiting.

Carfax reports on
Most, but NOT ALL, accidents.
Salvage/Junk titles
Flood damage
Odometer readings
Lemon histories
State emissions inspection results
Pass/fail inspection status
Damage reports from accidents
Major repair and maintenance data
Police-reported accident detail
Open Recalls
City/State of owner
Original vehicle use (rental, taxi, lease, etc.)
Lien information
Maintenance/service data
Vehicle registrations
Junk Titles
Stolen Vehicles
Odometer Rollbacks

Autocheck tries to do the same - but they have a couple hundred sources of data compared to Carfax's 20,000 sources.