With Labor Day in the rearview mirror, so too is the summer travel season. Vacation days from here on out are likely to be spent on Thanksgiving drives to grandma’s house and some rest and relaxation around the December holidays.

That means visits to national parks are likely to wind down. But that doesn’t mean there won’t be a lot of attention focused on total attendance numbers for the national park system.

With the Great Recession in full force in 2009, President Obama put on a full court press to get folks into our national parks. The result: nearly 275 million visitors entered through the gates of what Ken Burn’s called “America’s best idea.”

After a simple look at some data, I noticed that perhaps Wall Street investors should be looking at national park visits as an economic indicator.

Simply put, I compared two sets of data, the yearly unemployment rate and the Department of Interior’s yearly attendance levels for the national parks. Here are a few things I noticed:

The first high unemployment numbers following World War II were in 1958 when 6.8 percent of Americans were out of work. Essentially, the recession of 1958 coincided with the first year since World War II that national park attendance dropped. About 65 million visitors entered the parks in the summer of 1958 compared to 68 million the year before. So this would make the case that less money in Eisenhower-era American wallets meant fewer family vacations. But that trend simply didn’t hold a few years later.

In 1961, the United States saw another spike in unemployment from 5.5 percent the year before to 6.7 percent. This same year, national park attendance spiked from 79 million visitors the year before to 86 million in 1961. This exact same effect took place in 1975 when unemployment increased to 8.5 percent and national park attendance skyrocketed by nearly 20 million visitors compared to the previous year.

The converse of this trend proved true in 1977, 1978 and 1979. As unemployment numbers decreased each of these years, so did attendance levels in the parks.

But then there are the years 1982 and 1983 when unemployment was well over 9 percent. Attendance did grow in 1982, but in 1983 it had a slight drop off. You could say that these years may just be outliers, like 1958 perhaps.

The 1990s restored the idea that a growing economy equals shrinking national park numbers. During 1993, 1994 and 1996 both unemployment numbers and attendance levels fell.

So the trend is a trend right? Well, maybe not. Everything got murky during the last decade, when yearly attendance drops in 2001, 2002, and 2003 occurred while the unemployment rate rose. But as the economy tanked at the end of the decade, near record attendance levels were recorded in both 2008 and 2009.

All in all, it seems that in general, a bad economy is good for national parks. But, the data shows there are exceptions to the rule.

So, while Wall Street keeps its eyes glued to the latest unemployment numbers each week, perhaps it should simply call the national park system to better gauge the economy. Moreover, if Wall Street folks want to fix the numbers, maybe they should just keep people out of the national parks.