When Montana Sen. Max Baucus announced last week that he would not seek a seventh term in 2014, Montanans instantly began debating his legacy. After nearly 35 years in the Senate and four in the House, Baucus’ reputation as a conservative Democrat who straddled party lines is well established, and his mediocre lifetime score of 68 percent from the League of Conservation Voters reflects his political history.

Yet when Baucus released his priority list for his final 18 months in office, he promised to back legislation “to keep the Rocky Mountain Front the way it is for future generations.” Environmental critics shouldn’t be surprised, however, because when it comes to protecting Montana’s public lands, the senator has always been there.

“Having worked with him closely in Montana, he really does love the land,” says Jamie Williams, president of The Wilderness Society. “He really has made his mark in land conservation. That has been a consistent theme over his career.”

In 1973, Baucus was elected to the U.S. House, representing Montana’s Western District. He won by walking 600 miles across the district from Yellowstone National Park to the Yaak River Valley. His first conservation victory came quickly, with the passage of a bill in 1975 that designated all three forks (219 river miles) of the Flathead River as part of the Wild and Scenic River System.

After only four years in the House, Baucus was elected to the U.S. Senate in 1978. He was a steadfast supporter of wilderness in those early years, passing bills to create the Rattlesnake Wilderness and Recreation Area (32,976 acres) in 1980, and the Lee Metcalf Wilderness Area (259,000 acres) in 1983. He also passed a bill in 1988 that would have protected 1.43 million acres of wilderness if it hadn’t been pocket-vetoed by President Reagan.

The political fallout from the failure of that bill was severe, and Montana’s congressional delegation failed to find consensus on wilderness bills in the ‘90s. The ensuing years were the most politically challenging of Baucus’ long career. In 1996, he narrowly avoided defeat at the hands of future Montana Congressman Dennis Rehberg, and from 1997 to 2006, he was the only Democrat elected to federal office in Montana.

These years were a long, cold winter for conservation in Montana, with Baucus offering the only hope for a thaw. That thaw began with the election of Democratic newcomer Jon Tester over incumbent Republican Sen. Conrad Burns in November of 2006. During the lame duck session that year, Baucus managed to attach a rider to a large tax and finance bill, which withdrew over 400,000 acres of federal mineral leases along the Rocky Mountain Front. Two years later, he passed a bill securing $250 million in federal bonds to advance the Montana Legacy Project, a historic purchase of 310,000 acres of Plum Creek Timber lands in the Swan and Blackfoot river valleys.

Baucus continued to make conservation a top priority after winning re-election easily in 2008. In January of 2011, he introduced the North Fork Protection Act to withdraw federal minerals leases from the North Fork Flathead River Watershed. In October, he introduced the Rocky Mountain Front Heritage Act, which would create 67,000 acres of new wilderness areas and include 208,000 acres in a conservation management area.

With $5 million dollars in the bank for the 2014 cycle, Baucus appeared ready to take on all comers. Then, on April 17 this year, he made a controversial vote against the expansion of background checks for gun sales. The vote sparked heavy criticism, which some say triggered Baucus’ decision to resign days later. But there is another theory that might explain his decision, one that a senior Baucus staffer shared with me last week. On that April day, Baucus watched as Frank Lautenberg, the 89-year-old senator from New Jersey, cast his vote from a wheelchair. An aide had to lift Lautenberg’s hand to help him press the appropriate button.

Baucus is now 71 and has spent over half his life in Congress. He’s cast nearly 12,000 votes. Maybe he’d like to retire before he, too, ends up voting from a wheelchair with the help of an aide.

As he announced his resignation, Baucus declared that he wanted to continue serving Montana for the next year and half “unconstrained by the demands of a campaign. “Then,” he said, “I want to come home and spend time with Mel, my son, Zeno, and our family, enjoying the Montana public lands we’ve fought hard to keep open and untarnished.”

It will be many years before Montanans finally agree on the nature of Baucus’ legacy. But one thing is inarguable: He worked to protect well over a million acres of public land in Montana –– all of it land that faced a very uncertain future when he took office in 1973. When he and his family return home in the winter of 2014, I hope we can all agree to say, “Thanks, Max,” should we see him out on the trail.

Gabriel Furshong is a contributor to Writers on the Range, a service of High Country News (hcn.org). He lives in Missoula and works for the Montana Wilderness Association.