A century ago, Congress created the National Park Service to maintain and enhance America’s natural and historic preserves. It was needed. The inventory had grown since the designation of Yellowstone in 1872.

Since then, attention from Capitol Hill has faded. We won’t hear Hillary or Donald woo voters by pledging fealty to the NPS. Parks are as valued as ever, but have no vocal constituency.

Mississippi has several. We know their names:

• The Natchez Trace is the one motorists encounter most often. That’s because it extends from, well, Natchez in southwest Mississippi up and across the state, thence to Nashville. It crosses us like a beauty queen’s sash, following a pathway charted by Native Americans and adopted by settlers.

• Shiloh National Military Park, north of Corinth and near the Tennessee line, is where soldiers, blue and gray, sustained 23,746 casualties. That total — in only a few days of combat — was more than all casualties sustained in all America’s previous wars combined.

• Vicksburg National Military Park forms a crescent around the hill city, tracking lines of the summer siege that historians say determined the future of the nation.

• Two additional sites — Brice’s Cross Roads near Baldwyn and Tupelo National Battlefield — also relate to significant events of the Civil War.

• There are National Heritage Areas for the Delta, the Hills and the Gulf that tell the stories of hot tamales, Elvis and the “ethnic gumbo” that populates coastal Mississippi.

• There is an NPS Historic Park in Natchez and the mostly wet Gulf Islands National Seashore with bases of operation in Ocean Springs and Gulf Breeze, Fla.

In total, there are 410 National Park Service-managed properties across the landscape as well as in Alaska and Hawaii.

Their greatest value is that they exist as repositories of all things that define America as a place and us as a people.

But there are nuts and bolts considerations, too. The agency has 20,000 regular and seasonal employees and operates on a $2.6 billion budget.

A bit more about those funds: For the past eight years, cash allocated by Congress has declined and the gap, more and more, has had to come from “user fees.”

It is true that most parks were free, at least at the outset. Gradually, many changed. Token fees were imposed at first, followed by periodic “adjustments.” Today, it costs $12 per car to enter the Vicksburg National Military Park.

Some park properties remain free of fees, often because it would be impractical to collect. The Natchez Trace is a good example. Given the dozens of entry and exit points along its 444-mile length, that’s a lot of toll booths, even if automated.

Still, the fees that have been collected, legions of volunteers and volunteer donations have kept the NPS going in an era of increasingly lean federal allocations.

Next on the horizon, according to Johnathon P. Jarvis, NPS director, may be corporate sponsorships. Perhaps they will take the form of added signage, making it difficult to take a photo of Bloody Pond at Shiloh without an AT&T logo in the frame. It could become tough to line up the kiddies at the Grand Canyon without including McDonald’s golden arches.

Some are aghast, quite naturally, at the prospect of crass commercialization of sacred spaces and natural vistas. Others realize (2) Congress isn’t going to loosen up and (2) increasing user fees risks making park visits cost-prohibitive. Got to do what you’ve got to do.

The lesser but still significant importance of the NPS is that in addition to managing cherished places, the parks provide an economic plus.

Official numbers say visitor spending within 60 miles of a park property added $27 billion to the American economy in 2014 and supported 240,000 private sector jobs.

Mississippi numbers are impressive. The tally was 6.4 million visitors who had to eat, buy fuel and perhaps made an overnight state.

And for just one park — Vicksburg — there were 573,252 visitors in 2012 who spent $30.8 million in nearby communities.

Mississippi has its own great network of state parks, recreation areas, preserves and wildlife management areas.

The National Park Service properties differ in that they are state assets that don’t take a nickel from the state budget.

We should notice that.

Charlie Mitchell is a Mississippi journalist.