Free Load Boards for Trucking: Power Only

https://www.nexttrucking.com/  Based out of LA, power only trucking options

https://cargomatic.com/ local trucking


https://convoy.com/ claims you can sign up and start hauling in minutes.  App. based

https://www.chrobinson.com/en-us/carriers/  My buddy works for this company
Link to FAQ for carriers

https://schneidercarriers.com/find-freight

https://www.hubgroup.com/highway-carriers/

https://www.123loadboard.com/find-loads/

https://full-truckload.xpo.com/

https://www.directfreight.com/home/loads/search

https://www.pamtools.com/load/ppo


http://www.starfreight.com/carriers.html

Others to check out:
Trucker Path
Trulos
DSSLN
Live Loads
Load Up
Freight Finder
Landstar