In a watershed moment, more than half of the population now oppose drilling in the American wilderness — although this likely has more to do with cheap gas prices than a sudden embrace of environmental sensitivity.

According to poll data released by Gallup on Friday, the same day Donald Trump approved construction of the controversial Keystone XL oil pipeline, 53 percent of Americans oppose opening federal lands for oil exploration, compared with just 34 percent who were against the idea five years ago.

What changed? Gallup suspects declines in the oil market, which have kept a lid on gasoline prices, might be behind our newfound concern for the welfare of those amber waves and purple mountains.

We Love Cheap Gas

In March of 2012, when Gallup pollsters first asked the question, gas prices were significantly higher than they are today. “At that time, a gallon of gasoline averaged $3.91, according to the U.S. Energy Information Administration… the most recent estimates, from February 2017, show gas averaging $2.42 a gallon,” the poll report says.

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“Generally we see that when prices are low, there’s much less concern related to supply and demand,” said Jeff Lenard, spokesman for NACS, the National Association of Convenience Stores.

There does seem to be a link between lower gas prices and higher consumer confidence. The Pew Research Center analyzed gas prices next to the University of Michigan’s consumer sentiment index, and found that when prices go down, confidence goes up.

And gasoline prices have an outsized effect on our collective psyche. “For most people, the fraction of their income they spend on gasoline is actually quite small,” said Lutz Kilian, economics professor at the University of Michigan.

In 2012 — two years before prices started tumbling — the average household spent $2,912 on gas, or about 4 percent of pretax income, according to the U.S. Energy Information Administration.

Related: Appeals Court Refuses to Halt Dakota Access Pipeline

But prices at the pump take on greater significance for a couple of reasons, Kilian said. “To some extent, it’s because everybody is telling consumers how important the price of oil is,” he said, despite the fact that oil and gas prices don’t always move in tandem.

For drivers, gas prices are front and center — literally, by way of signs at nearly every gas station. “It’s a very visible price,” Kilian pointed out. The constant reminders reinforce our views and the sentiments they trigger.

But We Still Love the Environment

Today, we’re worrying less and willing to spend more. Gallup found that just over a quarter of Americans say they worry "a great deal" about being able to obtain and afford energy; five years ago, nearly half of respondents said the same. NACS found similar results in its new survey: The number of people who choose particular gas stations based on price fell by six percentage points, and there was a nearly identical increase in the number of people who choose where to buy gas based on snacks, sundries or other convenience-store items.

Our renewed economic confidence doesn’t just show up at the gas pump or convenience-store register: We gave a collective $10.7 billion to charities with a focus on the environment or animals in 2015, a 6.5 percent increase from the year earlier, Charity Navigator found.

Lenard suggested the prolonged slump in oil and gas prices could be giving Americans pause as our preoccupation with price recedes. NACS found that the number of people who say low gas and oil prices are good for the U.S. economy dropped by seven percentage points over a two-year span. ”The longer something happens, the more you think — what are other consequences?” he said.