A skateboard can be taken on as a carry on item. I have added the policy for your reference:
Skateboard, may be substituted for a carryon or a checked bag. If the skateboard fits under the seat, it does not need to be in a bag or covered, but it does have to be stowed with the wheels up so that it doesn't roll. If stowed in an overhead bin, a skateboard must be stowed with the wheels up and needs to be in a bag or have the wheels covered (trash bag is acceptable) so as not to damage other articles.
I hope this information helps
other experts are backing this answer
Thank you this was very helpful
Reservations agent for Southwest Airlines, leaping over policies with a single bound. faster than a speeding refund policy, saving luggage one bag at a time.