A US ban on Carnival Corp would hurt not only the company but dozens of local economies, experts say.

A federal judge may temporarily block the world's largest cruise line from docking at US ports as punishment for a possible probation violation related to environmental wrongdoing.

Carnival's nine brands sail to and from dozens of US ports, from Honolulu to Seattle to US Virgin Islands, including several each in Florida and Alaska.

"It could be a catastrophe," says Carl Berkowitz, a US-based cruise litigation consultant.