Move New Jersey to the intermountain West and put a fence around it – that’s the amount of federal public land that might as well not be public, according to a report released this week.

In its report, the Denver-based Center for Western Priorities calculated that more than 4 million acres of federal public land in six western states isn’t accessible to the public.

CWP workers used GIS technology to quantify the amount of inaccessible Bureau of Land Management and U.S. Forest Service land in Montana, Idaho, Wyoming, Colorado, Utah and New Mexico.

Land was considered inaccessible if it had no road or trail easements to allow the public to reach the land.

Based on those criteria, Montana has the largest total area of the six states: almost 2 million acres or more than 3,000 square miles without access.

More than 1.2 million acres in Montana are completely landlocked by private lands and 724,000 acres are inaccessible because crossing at the corners of checker-boarded public land is illegal.

Wyoming comes in second with more than 750,000 inaccessible acres, and New Mexico and Colorado have about 540,000 acres each.

“We have extraordinary public lands that the public can’t even set foot on, let alone use for hunting, fishing, or camping, the activities that are synonymous with our beloved public lands,” said Trevor Kincaid, Center for Western Priorities’ executive director. “Keeping people locked out of the land they own is like letting a ’57 Corvette rust in your backyard: just a waste.”

The amount of inaccessible land may be even greater because the report couldn’t include areas that have road access that has been legally or illegally closed by a landowner.

In addition, the report doesn’t include some areas that are essentially inaccessible because the only access is many miles out of the way.

The authors highlight two Montana locations that are landlocked due to road closures: Salmond Ranch Road and Bullwacher Road.

The Salmond Ranch Road is one of the few access points along 130 miles of the Rocky Mountain Front between Augusta and Glacier National Park. The first few miles run through the ranch before entering public land.

After the Salmonds locked a gate on the road in 1988, Teton County, the Montana Department of Natural Resources and the State Land Board have worked to prove that a legal right of way exists along the road.

In northeastern Montana, Bullwacker Road has provided decades of access to 50,000 acres of BLM land around the Missouri River Breaks National Monument.

In 2011, a court ruled in favor of a landowner who gated the section of the road that runs through his ranch, eliminating access to much of the area.

The authors point out that recreation on public lands contributes to each state’s economy.

In Montana, consumers spend around $5.8 billion on outdoor recreation, while in Colorado and Utah, the revenue jumps to between $12 billion and $13 billion, according to a 2012 Outdoor Industry Association report.

So adding more access to public land might bump those figures up.

The government has some tools to unlock the lands, but they may be lost if Congress can’t break through its deadlock.

The Land and Water Conservation Fund, passed in 1985, uses oil and gas tax revenue to protect public lands and enhance access.

The fund is set to expire in 2015 and often hasn’t been funded to its full amount - $900 million. But it provides money that can be used to work out deals with willing landowners and the authors urge its renewal.

They also encourage the renewal of the Federal Land Transaction Facilitation Act, which expired in 2011.

FLTFA authorized the land agencies to sell less-desirable public land so they would have money to buy high-priority lands, especially those that enabled access.

Newer legislation includes the Hunt Unrestricted on National Treasures Act introduced in September. The HUNT Act would, if passed, direct land agencies to quantify their inaccessible lands – much like this report did – and develop policy to focus efforts to gain access.

“This is not an insurmountable access obstacle,” said CWP policy director Greg Zimmerman. “There are viable, commonsense solutions available at our fingertips that will open the gates to 4 million acres of treasured public space.”