JAFFREY, N.H. (AP) — On Mount Monadnock, hikers file up the 3,165-foot peak in lockstep, protected from drizzling rain by a luminous golden canopy of leaves. They’re not just gazing at foliage — they’re looking at cold, hard cash.

Money really does grow on trees in autumn in New England, and all six states are raking it in. Officials say tourists will spend upward of $3 billion to catch a glimpse of the red, yellow and orange hues — and the windfall is steadily rising as the economy regains strength.

Every year, the radiance of fall draws nature-lovers to Monadnock State Park — and countless other mountains, hills, scenic look-outs and shady country lanes — by the droves.

“We wanted to get out in the fresh air and see the colors while it’s still warm,” said Christopher LeBeau, who drove from Connecticut to hike Mount Monadnock. “This is full peak here, and it’s amazing.”

Lingering warm weather is causing leaves to stay on the trees longer in New England. Some experts say 2014 could be an outstanding year for foliage, aesthetically and financially.

The New Hampshire Division of Travel and Tourism Development projected the state would see 8.2 million visitors this fall, and they’re expected to spend $1.6 billion. In 2009, New Hampshire had 7.5 million fall tourists and spending totaled $1 billion.

Vermont had 3.6 million fall tourists and $460 million in spending in 2011, the last year for which comprehensive figures were available, up from $331 million in 2009 with roughly the same number of people visiting. Visits to state parks in the Green Mountain State will surpass 950,000 this year, an increase of 8 percent and the highest visit count since 1989, tourism officials said.

The fall season accounts for a quarter of annual tourist spending in Vermont. And with this autumn providing an exceptionally brilliant show, the state is seeing a strong turnout.

“The weather has been excellent this year, and we’re expecting a longer season,” said Megan Smith, Vermont’s commissioner for tourism and marketing. “If we can show these colorful leaves are out, through our website or social media, then people will drive from Montreal. They’ll drive here from Boston.”

Smith said Vermont fall visits have grown between 3 and 6 percent every year since 2009, when the recession that hit in 2007 bottomed out.

Though states calculate tourism spending using different metrics, two key factors are hotel bookings and money spent on restaurant meals.

“We were hit pretty hard and hotel rooms and meal taxes were off” during the recession, said J. Gregory Gerdel, chief of research for Vermont’s tourism division.

In Maine, spending is up about $92 million since 2009, when autumn visitors brought in $489 million. Last year, they spent $581 million, according to state tourism department figures.

“Weather and foliage alike have been quite exceptional this year with vibrant color,” said Carolann Ouelette, director of Maine’s office of tourism. “Cruise ship traffic helps add to the numbers, and from what we have heard, fall events have seen strong numbers across the state.”

States have been devoting money and manpower to marketing campaigns in hopes that fall visitors who come for the foliage stay for some of their other attractions: craft beer tasting in Vermont, history in Connecticut and mansion tours in Newport, Rhode Island.

In southern New England, where peak foliage generally lasts from late October until mid-November, Massachusetts has the region’s largest market for fall tourism, with $2.8 billion in spending in Sept.-Oct. 2013 — up from $2.2 billion in the same period in 2012 — the state tourism office’s research division said.

Massachusetts officials don’t distinguish how much of that money is spent by visitors drawn by the foliage as opposed to Boston or the Cape Cod beaches. Because of budget constraints, Rhode Island only tracks tourism spending on an annual — not seasonal — basis; and cash-strapped Connecticut is expected to release figures in December dating back to 2006, the last time it took a hard look at travel in the state.

At Concord, Massachusetts’ historic Walden Pond, the inspiration for Henry David Thoreau’s “Walden,” leaf-peepers took advantage of a long Columbus Day weekend, even though peak season was still a week off.

“I drove up here from New York to see the fall colors, and I chose Massachusetts because of all the historical sites here,” said Glenn Cronick, of Staten Island. “I haven’t been here in the fall before, so I had to see it.”