George Rogers Clark National Historical Park, near Vincennes, Indiana, preserves the site of one of the greatest American military achievements of the Revolutionary War. In February 1779 a small force of irregulars under the command of Col. George Rogers Clark endured terrible marching conditions (sometimes wading in icy swamp water up to their shoulders) before capturing British-held Fort Sackville at Vincennes, an improbable feat that helped drive the British from the old Northwest Territory and bring France into the war on the American side. While the precise location of Fort Sackville hasn’t been determined yet, it’s thought to be somewhere in the park.

When you peruse the annual visitation data for this park, you are reminded that, where identifying trends is involved, a lengthy period of record is much more useful than a brief one, and a single year’s visitation total can’t tell you much at all.

During 2008, George Rogers Clark NHP tallied 113,688 recreational visits. Viewed against the backdrop of visitation for the 41 other national historical parks and the 80 national historic sites in the National Park System, this really isn’t too bad. Many of those other NPS units get fewer than 113K visits a year, and some get a lot fewer (First Ladies National Historic Site, for example, recorded just 9,770 visits in 2008).

The 2008 tally at George Rogers Clark was just 0.8 % less than the 2007 tally of 114,560. I doubt that’s even statistically significant, and even if it is, a visitation decline that’s of rounding error size is nothing to get too excited about. Moreover, many National Park System units suffered no-doubt-about-it attendance declines last year and would love to trade for the more nearly stable attendance situation at George Rogers Clark.

But wait. The picture skews sharply to the negative side when you take the longer view. George Rogers Clark’s 2008 visitation was 11 percent less than the average of the last ten years, 15 percent down since 2004, and a whopping 41 percent smaller than the 1997 peak visitation of 194,292. Viewed as a trend line on a graph, this information takes on an ominous character. It practically shouts “something has to be done!”

The Park Service can do a number of things to boost sagging attendance at a park, and one of these proactive measures is to get rid of the entrance fee. This was done at George Rogers Clark. last October when the $3 admission fee was eliminated and the park went to a year-round free admission policy for the first time since it began collecting entrance fees in 1988.

Given the strain on household budgets these days, removing even so small an impediment as a three-buck admission charge should make a difference. It’s doubtful, however, that adopting a free admission policy can restore annual visitation to anything near that of the park’s late 1990s heyday.

Frank Doughman, the park’s chief interpretive ranger, told me that any improvement in the park’s attendance attributable to the shift to free admission is likely to be small in scale and brief in duration. He believes -- quite rightly, I think -- that broad-scale shifts in the interests and behavioral dispositions of the American public are working against historic site visitation. “These days,” he said, “people, especially young people, have lots of diversions and are just not as interested in history as people used to be.” Sadly, even school group visits to the park have declined, and there never has been a fee levied for those.

Postscript: The phone number of the main desk at George Rogers Clark National Historical Park ends in “1776”. Pretty cool, huh?