Drivers and passengers in cars with loon license plates will receive free admission to state parks and historic sites this Saturday and Sunday.

For the second year in a row, the Maine Department of Conservation is waiving state park admission fees as a measure of thanks to those who pay extra every year for the license conservation plate featuring a loon.

Since the program’s inception 12 years ago, the loon plate has funneled more than $13 million to the Department of Conservation and the Department of Inland Fisheries and Wildlife, which share the proceeds.

The DOC uses the money to make improvements at state parks and historic sites, including improved access roads and parking. DIF&W uses the funds to support management of nongame, rare, threatened and endangered species.

More than 75,000 registered vehicles in Maine display the loon plate. But that figure is down from more than 100,000 in the 1990s.

DOC spokesman Jim Crocker said recently that the state will be taking another look at the loon plate as the oldest plates start reaching an age when they may need to be replaced. One option being batted around is replacing the loon on the plate with a moose.

Crocker said no decision has been made about whether to change the loon plate.