Gerald Halpin in front of the Freddie Mac building in Tysons Corner in 1999. (Shawn Thew for The Washington Post)

Gerald T. Halpin, the first real estate developer to build in Tysons Corner and one of the most prolific and successful developers in the Washington area, died Aug. 14 in Jackson, Wyo. He was 94.

His daughter, Christina Halpin Bourdeaux, confirmed the death but did not disclose the cause. Mr. Halpin moved to Jackson from Fairfax County, Va., a few years ago.

The son of an elementary school custodian who had gone bust during the Great Depression, Mr. Halpin developed more than 100 major real estate projects during a career spanning more than five decades. They included four major projects at or near Tysons Corner and several thousand apartments in Northern Virginia.

“Jerry Halpin is Tysons Corner,” said Bill Lecos, former president of the Fairfax County Chamber of Commerce, told The Washington Post in 2009. “He and few others are the creators of Tysons. He’s defined it for the last 40 years.”

At the peak of his career, Mr. Halpin either founded or headed more than 100 real estate corporations and partnerships. His company, West*Group Management LLC, developed more than 14 million square feet of office space, most of it in the Washington area.

Mr. Halpin directly supervised all activities in the finance, accounting, planning, legal, construction, property management, business development and corporate administration departments.

Mr. Halpin always began projects with OPM — “Other People’s Money, since I didn’t have any,” he once said.

Gerald Thomas Halpin was born in Scranton, Pa., on Feb. 15, 1923. As a boy, he sold cherries, apples and currants from the family’s back yard to residents of wealthier neighborhoods. His father allowed him to keep half the money.

Mr. Halpin paid his way through night classes at what is now the University of Scranton by working as a plastics manufacturer and glass blower. He served in the Navy during World War II, where he learned building trades and carpentry as a member of a construction battalion. Mr. Halpin and his fellow Seabees supported Marine Corps invasions in the Pacific.

After his discharge in 1946, Mr. Halpin enrolled at Syracuse University on the GI Bill. He painted houses to cover expenses and saved what he could. The savings staked him to two rooming houses. He lived in one and rented out the other.

Mr. Halpin met his future wife, Helen Richter, at Syracuse. After he graduated in 1950, he sold the rooming houses for a modest profit and moved to Northern Virginia, where his wife had been hired as an accountant and secretary by Atlantic Research Corp.

Mr. Halpin enrolled at Georgetown University Law School and worked on the side as a credit investigator and a carpenter. He also was already an accomplished poker player, a skill that led to his career in real estate.

One evening, while still in law school, he emerged the big winner in a game that included Atlantic’s president. The man was impressed and asked Mr. Halpin to oversee ARC’s business operations. Mr. Halpin never went back to classes.

He first cut his teeth on Fairfax County real estate during his decade with ARC. The company wanted to expand into Alexandria, Va., but available land was too expensive. Mr. Halpin learned of an 89-acre parcel at Edsall Road and Shirley Highway and bought it on behalf of ARC for $600,000.

The firm built its headquarters there in 1958 — a distinct building with a parabolic roof that looked like a bicycle seat. Meanwhile, Mr. Halpin and his wife bought a piece of land in nearby Springfield.

Mr. Halpin built much of their house himself.

Besides his wife, of Jackson, survivors include three children, Peter Halpin and Michael Halpin, both of Jackson, and Christina Halpin Bourdeaux of Cape Elizabeth, Maine; a sister; and seven grandchildren.

In 1960, Mr. Halpin founded West*Group’s predecessor, Commonwealth Capital, with three partners who had been colleagues at ARC. The men developed Landmark Center, a 700,000-square-foot shopping mall in Alexandria.

But Mr. Halpin had his eye firmly on Tysons at the same time. In 1962, he and his partners made a deal with the Ulfelder family — dairy farmers who owned 125 acres just east of the now-famous intersection.

The parcel soon became West*Gate — fueled by an insurance company’s “OPM.” By 1970, 20 research and development companies were operating out of the complex.

By the mid-1970s, West*Group owned and managed 560 acres of office campuses at West*Gate and West*Park. Much of the space was — and is — leased to federal government agencies and to consulting firms that do business with them.

In 1976, West*Gate’s assessed value was $16.6 million, making it the third most valuable commercial parcel in the country (Theodore Lerner’s nearby shopping center, at $19.6 million, was second).

In the 1990s, Mr. Halpin began to devote much of his time and energy to reimagining Tysons Corner.

He envisioned what he called a “mini-Manhattan” of varied and more densely built residential and commercial properties and worked diligently with county officials to plan it.

Mr. Halpin announced plans to replace the two-story “Wests” he had built there in the 1960s with taller, more dense developments. He also lobbied state and federal officials for an extension of Metrorail to Tysons, which was approved in 2002.

The publicity-averse Halpin was active in political and civic circles. In the 1970s, he served on a committee of Northern Virginia business leaders that successfully lobbied Richmond for Northern Virginia’s fair share of state tax revenue. In the 1980s, he was a founder and enthusiastic member of The 123 Club, a lobbying group named for the well-known highway in Vienna that arranged funding for George Mason University.

Mr. Halpin was also the first finance chair of the Wolf Trap Foundation and raised the bulk of the funds that built the 7,000-seat Filene Center in 1971. In 2005, he received an award from the Fairfax County Chamber of Commerce for his “invaluable contributions to the economy and quality of life in Northern Virginia.”

Much of his work late in life touched on the environment. He had chaired the Grand Teton National Park Foundation’s board of directors and served as a director of the National Fish and Wildlife Foundation. His hobbies were hiking, fishing and snowmobiling.

He was heralded by the Urban Land Institute and other organizations for being environmentally conscious in his development work. But his vision for the future of his company and Tysons Corner itself was one of continued construction.

“The Washington area is the world’s capital of democracy,” he told The Post in 2003. “It’s going to keep growing. As much as you may not like the people and the traffic, it’s going to keep coming, and we have to respond.”