The Riverside Press-Enterprise reports that the sign facing northbound drivers was supposed to show a road closure alert on Christmas Day. But Riverside County transportation official John Standiford says the message supporting the Republican presidential candidate remained for about 12 hours before it was changed back Saturday.
The county Transportation Commission said in news release that the sign had been placed along the road because of the 91 project, which is adding lanes and connectors between I-15 and State Route 91.
Standiford says the agency is taking additional security measures to prevent another hacking incident.
The hackers have not yet been caught.