After four years, a pilot program that sells electronic duck stamps might become a permanent if passed by the Senate.

There are currently eight states participating in the program, and if passed, the bill would give the U.S. Fish and Wildlife Service the ability to extend the sale of electronic duck stamps to hunters in all states, according to the Associated Press.

Originally created in 1934 by the U.S. Postal Service for the U.S. Fish & Wildlife Service, duck stamps are federal licenses that hunters over the age of 16 must buy in order to hunt migratory waterfowl. Even though stamps can be bought at a variety of locations, including sporting goods stores and online, they ultimately arrive by mail. Electronic stamps remain valid for up to 45 days while people wait for the actual stamp.

In addition to granting hunting privileges, duck stamps are important conservation tools. They currently cost $15 and 98 percent of all revenue generated from sales go toward purchasing or leasing wetlands. More than $750 million have been generated from sales since 1934, according to numbers from the Federal Duck Stamp Program. That money has been used to place more than 5.3 million acres of wetlands under the protection of the National Wildlife Refuge System.