During an economic address at the Detroit Economic Club, Donald Trump tailored some of his statistics to the local audience.

"As a result of recent Obama EPA actions, coal-fired plants across Michigan have either shut down entirely or undergone expensive conversions, making them non-competitive in many cases," Trump said. "The Obama-Clinton war on coal has cost Michigan over 50,000 jobs."

Trump has often criticized efforts by the Obama administration -- and those who find climate change to be a serious concern -- to wean the United States from fossil fuels by tightening federal environmental regulation of coal-fired power plants. Here, we’ll take a look at the second part of Trump’s statement: "The Obama-Clinton war on coal has cost Michigan over 50,000 jobs."

This assertion initially caught our eye because we’d never thought of Michigan as one of the premier coal-producing states. Our suspicion was correct: According to the National Mining Association, Michigan is not on the list of 26 states that currently produce any amount of coal.

Meanwhile, according to the Bureau of Labor Statistics, the number of workers engaged in any type of mining in Michigan over the last decade has varied between 5,000 and 7,000, making it essentially impossible to have lost 50,000 existing jobs in that sector. And as the Washington Examiner has noted, Michigan has fewer than 20,000 people working in the electricity generation sector today. So the scale of the job losses Trump cites seem, at least at first blush, to be unlikely.

So what was Trump trying to say? The prepared version of his speech includes a footnote that points to a news release from the National Mining Association published almost five years ago, on Sept. 7, 2011.

Here are some excerpts from that news release, which criticized "Beyond Coal," a campaign against coal-fired power plants coordinated by the environmental group the Sierra Club and cited a study the group released:

"The destructive impact of the ‘Beyond Coal’ campaign is most clearly evident in the following 10 states where power plants blocked by the club represent the highest number of potential jobs (construction and permanent) foregone: Illinois (126,612), Texas (122,065), Montana (114,102), Nevada (75,194), Florida (75,055), Ohio (70,371), Colorado (55,620), Michigan (53,587), Oklahoma (42,581) and Kentucky (38,824)."

In response to an inquiry from PolitiFact, Andrew Wheeler, an energy adviser to the Trump campaign, also pointed to a U.S. Chamber of Commerce analysis that found that 10 delayed or canceled projects in Michigan -- most of them coal-fired plants -- would have created 56,000 jobs up front had they been built.

Between the 53,000 jobs cited by the National Mining Association and the 56,000 jobs cited by the U.S. Chamber of Commerce, Wheeler said, "it is obvious that the ‘over 50,000 jobs’ cited by Mr. Trump is accurate."

But just because a campaign is able to footnote a specific number doesn’t mean that the number is meaningful, or as fully contextualized as it ought to be.

Here are a few important things to know about this number.

• The number refers to "potential" jobs lost, not actual jobs lost. This is an important point that would not be obvious from the way Trump phrased his statement. By leaving the impression that these were actual jobs lost, Trump’s statistic invites a degree of outrage that isn’t warranted.

And there are good reasons to be cautious about future job projections, especially when they have been framed so broadly as to include vendors to the industry, rail transport, ports and machinery manufacturers.

Any job projections of this sort are subject to rosy estimates -- especially if a group has a vested interest in the issue. In making an argument to the public, all groups will put forward their most favorable case.

Trey Pollard, the national press secretary for the Sierra Club -- which has its own dog in the fight -- said the number of plants being counted by the mining association are essentially "the coal industry’s wildest dreams" -- a reflection of circumstances in which they can build coal plants "in any community they want to."

• The number doesn’t reflect that coal is increasingly being replaced by natural gas. Trump’s decision to use this number tells only part of the story of how the electricity sector has been developing.

In recent years, according to federal statistics, coal has been losing ground to natural gas and, to a lesser extent, renewable energy when it comes to electricity generation.

A July 2016 analysis by Sam Evans of the School of Business and Economics at King University in Bristol, Tenn., found that environmental regulation has been a factor in this switch, but a "secondary" one.

"The recent decline in the generation share of coal, and the concurrent rise in the share of natural gas, was mainly a market-driven response to lower natural gas prices that have made natural gas generation more economically attractive," Evans wrote.

• This isn’t just about Obama or Clinton. Trump ignores that much of the impetus in Michigan for switching away from coal has come from the state’s Republican governor, Rick Snyder, and from utilities themselves.

Snyder has generally continued his support for steps to shift away from coal that began under his Democratic predecessor as governor, Jennifer Granholm. In 2015, Snyder said at an energy conference that "now is the time to look at a long-term transition away from coal," adding that because of the state’s natural gas infrastructure, "we're well positioned to actually have a fair amount of that coal demand go to natural gas."

And Gerry Anderson, the chairman and CEO of DTE Energy, an electric utility that serves more than 2 million customers in the state, has written that "we plan to retire older, less efficient coal plants and build new, cleaner natural gas power plants over the next decade."

Our ruling

Trump said that "the Obama-Clinton war on coal has cost Michigan over 50,000 jobs." However, this claim is problematic on several levels.

While the number matches one projection of how many potential jobs could be lost from the blockage of coal-fired plants, there’s a difference between actual jobs lost and potential future jobs lost. And the number cited -- an impossible-to-confirm projection based on broadly construed calculations released by a pro-coal group -- should be taken with a big grain of salt.

Trump also ignores that market forces, not just environmental regulations, have driven many of the job losses in the coal sector, and he also ignores that Michigan Republican officials and utilities themselves -- not just the Obama administration -- have pushed the switch away from coal. We rate the claim False.