Back in 1986, as Congress engaged in a last-minute scramble to fund the government, a Republican congressman from Pennsylvania slipped an earmark into a massive funding bill, turning a small exhibit of steam-powered trains — known as Steamtown USA — into a national park. Three decades, nearly $100 million, and one congressional earmark ban later, that project continues to cost taxpayers millions of dollars annually.

The “Bridge to Nowhere,” the North Carolina teapot museum, the indoor rainforest in Iowa, and yes, Steamtown USA, were among the many egregious earmarks that led fed-up taxpayers to press for a ban on such spending. Like triceratops and velociraptors, earmarks were declared extinct, fossilized relics of a bygone era.

But what taxpayers and many in Congress don’t realize is that, despite a successful ban on new earmarks, we are still paying millions of dollars for the old ones. Through unexpended funds, carve-outs in the tax code, and grant awards, spending on past earmark projects and their recipients still roams the federal budget landscape.

Today I am releasing a report, Jurassic Pork, which will highlight the fossilized pork projects still embedded or buried in the federal budget. It should serve as a reminder of the past scandals that brought about the extinction of earmarks, and as a warning that the cost of earmarking often long outlives the practice itself.

Jurassic Pork digs into just two-dozen of the many earmarked projects and recipients of congressional bounty that continue to cost taxpayers. Take for example the aptly named VelociRFTA, a bus rapid transit system in Colorado covering the 40 miles between Aspen and Glenwood that began as an $810,000 earmark. Since the earmark ban took effect in 2010, thanks to continued federal funding, this vestige has cost taxpayers $36 million.

Also highlighted is the American Ballet Theatre, which supplemented a flow of federal grant money with more than $800,000 earmarked from a member of Congress who also happened to perform in one of the group’s recent productions.

And then there are the 6,000 unspent highway earmarks representing $5.9 billion that sit idle in a Department of Transportation account. These include pork projects like the $600,000 Upper Delaware Scenic Byway Visitor Center in Cochecton, N.Y. Unfortunately for taxpayers, the visitor center ended up being built in Narrowsburg. Because the location was specified as Cochecton, the money will likely continue to sit on the federal government’s ledger.

Within these unspent transportation earmarks, there is a smaller group — often referred to as “orphan earmarks” — that have had less than 10 percent of their funding spent after 10 years. According to the Congressional Research Service, 70 earmarks worth more than $120 million remain on the books. In August 2015, more than 1,200 earmarks from the last major highway bill will officially hit “orphan” status, representing $2 billion in yet-to-be spent funds.

With a near-bankrupt Highway Trust Fund, Congress should find a way permanently park this unspent pork. To that end, I’ve also introduced the Jurassic Pork Act, which would rescind funding for orphan earmarks, and return that money back to the Highway Trust Fund.

Like John Hammond, the billionaire CEO of the failed theme park in the first Jurassic Park film, not everyone in Congress is content to leave these relics in the past. Not a year after the earmark ban was implemented in the Senate, then-Majority Leader Harry Reid (D-NV) proclaimed, “I’ve done earmarks all my career, and I’m happy I’ve done earmarks all my career.” Others from both sides of the aisle have argued that a return to earmarking would help lard up, or “incentivize,” votes.

But tax dollars don’t exist for political horse trading, nor as a reward for powerful members to dole out as tribute. Taxpayers should remain vigilant against these types of pleas for parochial spending and a return to pork as we knew it.

The moratorium on earmarks put an end to such shenanigans. But as readers of Jurassic Pork will see, the spending on their legacy continues. Taxpayers have already seen the ending of this movie. We don’t need to be treated to a sequel.

Jeff Flake is a U.S. senator from Arizona.