Raymond Plank, co-founder and longtime leader of the energy firm Apache Corp., was a colorful and influential figure on the Minnesota business scene from the 1950s to 1980s and a philanthropist of broad interests.

Plank died last Thursday at his home in Ucross, Wyo., where one of his foundations operates a highly regarded retreat for artists and writers. He was 96.

Plank grew up on a farm in Wayzata, was a combat pilot in the Army Air Forces during World War II and returned to the Twin Cities to start a tax-advisory firm. In 1956, the firm became Apache, which today is the nation’s second-largest independent producer by market capitalization.

The company was based in the Foshay Tower in downtown Minneapolis until 1987, when it moved to Denver and then to Houston four years later.

In a diversification into real estate in the 1950s, Apache built Apache Plaza in St. Anthony, the region’s second indoor mall after Southdale Center. The 60-store mall, a marvel of modernist architecture with a central court larger than a football field, was a fixture of Twin Cities shopping for decades. It was torn down in 2004.

Plank remained a leader of Apache until 2009, when he retired as its chairman.

“He was always on the move and driven and all about being productive and leaving the world a little better than he found it,” his son, Roger Plank, said Monday.

Apache evolved from the tax and financial advisory firm after Raymond Plank and his colleagues studied oil and gas exploration and recognized that investors could be better served through different structures. The firm’s name came from the initials of its founders — Truman Anderson, Plank and Charles Arnao — provided the A, P and A. A secretary suggested they add C, H and E to form Apache.

The company became an early proponent of an investment vehicle that became known as master limited partnerships (MLPs) to facilitate ownership in risky oil and gas properties. MLPs could be traded publicly and offered significant tax advantages to investors. MLPs popularized oil and gas investments that were previously largely confined to the rich, Mary Lyman, executive director of the National Association of Publicly Traded Partnerships, told the New York Times.

Apache stopped using MLPs for oil and gas properties after 1986 when a new tax law eroded their advantages. The company at the time was targeted by unwanted buyout offers, leading Apache to institute a “poison pill” defense and Plank to become a widely quoted opponent of corporate raiders.

In that same period, Apache was buffeted by ultralow energy prices and Plank also became an outspoken advocate for an import tax that would have put a $24 floor under the price of U.S. oil. The firm shifted away from selling energy investments and into more direct ownership of energy assets. The move to Denver put Plank and other top managers closer to assets they had acquired in the western U.S.

“Not only did it cost the Twin Cities 150 jobs, but it robbed us of one of the more cantankerous, controversial — and downright interesting — business executives this area has seen,” Star Tribune business columnist Dick Youngblood wrote at the time.

But it was a pragmatic move for the company. As the only oil and gas firm in Minneapolis, Apache would have had difficulty attracting the engineers and geologists it needed to oversee direct management of wells. “He was foresighted enough to see that if Apache had to get operations-type folks, that wasn’t the place that could attract them,” son Roger Plank said.

It happened just three years after Raymond Plank promised then-Gov. Rudy Perpich to keep Apache in the Twin Cities amid a heated public back-and-forth over the cost of doing business in Minnesota. Plank in the 1960s and 1970s often criticized the state’s tax and regulations, but he praised Perpich in the early 1980s for tax cuts and other improvements. Plank and David Roe, a longtime labor leader in the state, later co-chaired Minnesota Wellspring, a statewide civic group.

“Minneapolis was very special to him and to his family, too,” Roger Plank said.

Plank invested in a handful of small businesses in the Twin Cities in the 1980s, helping entrepreneurs navigate accounting and other matters. One of those firms was Garn Co., a maker of wood heating systems in St. Anthony, that survives today. Plank invested nearly $1 million at a time when Garn was ramping up manufacturing, then sold back his stake in the firm to owner Martin Lunde a few years later.

"He helped us get through UL certifications and handle insurance," Lunde said. "And we're still around today. Without him, I don't know if we would have been able to do it."

In a 1998 visit to the Twin Cities, Raymond Plank told Youngblood that candor sometimes got him in trouble. “As you know, I’m far more often wrong than in doubt on subjects that are important to me,” Plank said.

Those subjects were wide-ranging, and his philanthropy reflected that sprawl.

In 1967, following riots in north Minneapolis, Plank helped form the Urban Coalition, an economic and social justice organization. He later served on the board of the Way, a controversial storefront community center in north Minneapolis.

After Apache’s investments grew in the west, Plank started the Ucross Foundation and formed an artist-in-residence program on a 20,000-acre ranch in Wyoming. More than 2,000 artists, composers and writers have since been granted uninterrupted time and space to work at the ranch. He also funded creative grant programs for teachers in the U.S. and Egypt.

Plank endowed professorships at Carleton College and Harvard University’s Kennedy School. He was a major benefactor of the Blake School, which he attended, and of the Minnesota Historical Society’s restoration of Fort Snelling, where he enlisted in 1942.

Plank flew more than 40 combat missions from 1944 to the end of the war in 1945. When flights were canceled on Aug. 9, 1945, three days after a similar wave of cancellations for the atomic bombing of Hiroshima, Plank and a friend decided to make an unauthorized flight to try to see what they could from the air. They were about 80 miles away when they saw the second atomic bomb explode at Nagasaki.