With fewer Americans visiting national and state parks, Maine’s economic challenge is to encourage visitors to Acadia National Park and other outdoor venues to stay longer – and spend more money per visit.

The number of visitors to Acadia National Park dropped 23 percent between 1996 and 2006. Baxter State Park had 25 percent fewer visitors last year than a decade earlier, and the number of people using the Allagash Wilderness Waterway declined nearly 70 percent between 1999 and 2005. Similar trends have been seen in parks nationwide. Park officials blame factors as diverse as American workers having fewer days off to young generations more interested in video games than the outdoors.

Whatever the reason, the trend could be troubling for Maine, a state highly dependent on tourism, particularly those coming to enjoy the outdoors.

The number of out-of-state hunters and fishermen coming to Maine is also dropping. Nonresident fishing licenses have dropped from more than 83,000 in 2000 to fewer than 77,000 last year, according to figures from the Maine Department of Inland Fisheries and Wildlife. The decline in nonresident hunting licenses has dropped from 41,000 in 2000 to 37,000 last year.

Surveys done for the Maine Office of Tourism have long found that the state lacks some of the amenities sought by visitors and hence is not getting them to stay here as long as they might.

For example, according to a 2003 study of the area known as the Maine Highlands, which encompasses Greenville and Millinocket, 3 million people took day trips to the region, but less than 19 percent spent the night there. Statewide studies have found that people primarily visited Maine to travel through areas of scenic beauty and experience the natural environment and engage in outdoor activities such as camping, hunting, fishing, hiking or rafting.

However, Maine lacks high-end accommodations that many travelers, especially well-heeled baby boomers, desire. Without such hotels, restaurants and outfitters, the state is losing tourism dollars that it otherwise could attract.

These travelers may be interested in a day hike, sea kayaking or a canoe trip. At the end of the day, however, they don’t want to pitch a tent. They want to return to a well-appointed room, enjoy a fine meal, maybe get a massage, and sleep on a firm bed.

Maine should try to lure new visitors, as it does through advertising campaigns. Bigger dividends, however, are likely to be paid by encouraging those who already know and like Maine to stay longer. To do this, the state needs the amenities these travelers want.