Imagine staring across the Utah wilderness at those famous towering mesas and buttes. Now imagine a line of oil derricks in the middle of it. It’s an apocalyptic vision of an American landscape given over to the energy industry, and one that campaigners fear could become a reality.

A total of 27 parks in the US known as national monuments – which together account for more than 11 million acres of protected land in 11 mostly western states – are at risk of being reduced in size or losing their designation altogether following an unprecedented presidential order issued in April. Americans have until Monday to voice their opinions before the Interior Department makes its recommendations.

Among the monuments under consideration is Bears Ears in Utah, a 1.35-million acre area of stunning landscape harbouring 100,000 archaeological sites, many of which have never been studied. The land has been described as a “library of human history” and its cultural importance, not just to the US but worldwide, is the reason President Obama granted it national monument status in December 2016, following a campaign by a coalition of five local tribes. Now it is under threat.

Describing the creation of national monuments as “a massive federal land grab” that “should never have happened”, President Trump instructed Ryan Zinke, secretary of the interior to review 27 monuments of 100,000 acres or more created since 1996. A public consultation period ends on 10 July and secretary Zinke will make his recommendations in August.

The move sent shockwaves through the outdoor and recreation industries. This weekend campaigners are ramping up efforts to raise awareness of the threat via social media, ahead of the government consultation deadline.

“The scope of the threat is huge,” said Dan Hartinger, deputy director of parks and public lands defence for the Wilderness Society, which has over a million members across the US. “[It could impact on] everything, from the way they are promoted and staffed to these lands being opened to large-scale oil and gas developments. You might also see much more off-road vehicle use than you see now which could lead to erosion.”

More than one million Americans have submitted comments to the government consultation, but campaigners are worried that the issue is not as widely known as it should be, partly because of the deluge of other news, but also because the monuments themselves are not that well known.

“These monuments are hidden gems, yet they are comparable – in beauty, in history and in what they protect – to a lot of our national parks. Across the board these monuments are the best of the best,” said Kate Kelly, director of the public lands programme at US thinktank the Center for American Progress.

National Parks are created through legislation passed by Congress while national monuments can be established either by Congress through legislation or by the president, under the Antiquities Act. In total 157 national monuments have been created since the act was introduced by Theodore Roosevelt in 1906. Trump is the first president to suggest withdrawing protection.

The fate of the parks is unknown - until Zinke makes his recommendations – but campaigners say that the president does not have the power to undo designated monuments. “We are working with legal experts. If they act unilaterally to reduce or alter the monuments, they are breaking the law,” said Kelly. Trump has framed the review as a move to give control of the land “back to the people”, but Kelly – and other campaigners – believe his actions are “tied to the fossil fuels agenda”. The Center for American Progress has done its own research into the natural resources within the threatened monuments and found significant oil and gas reserves which, she said, “may explain why there’s a target on them”.

Individual campaigners throwing their weight behind the campaign include film-maker Brent Rose, whose #27Monuments Project is documenting a 6,000-mile road trip to visit as many of the 22 continental sites as possible (five of the 27 are marine sites) ; Utah-based skier Brody Leven; and trail runner Luke Nelson, who lives in Idaho and has spoken at rallies and at Patagonia clothing stores. Referring to the final social media push this weekend, Nelson said, “It’s really down to the wire now, but hopefully it’s enough.”

However, this is an issue that goes far beyond a love of the wild. These places are vital to the US economy and, in particular, tourism.

Designation as a monument increases public awareness of areas. Las Cruces chamber of commerce in New Mexico which was the driving forced behind the creation of the Organ Mountains Desert Peaks national monument in 2013 has reported an increase in tourism and press since its designation. “There would be a fear is that the benefits of increased visitation would be tamped down,” said Hartinger.

As Nelson put it: “When people think of the US they often think of big, wild, open spaces that nowhere in the world really has. If we start, as a nation, demeaning and depreciating those spaces, that takes away that uniqueness and could significantly impact economically on tourism - people will have less of a reason to come and visit if there are less of these places to come and see.”

• This article was amended on 11 July. It stated that national monuments can only be created under the Antiquities Act but they can also be established through legislation by Congress.