CRAZY HORSE, S.D. — It was to be the largest sculpture in the world: a granite portrait of a Sioux leader on horseback whittled out of a mountain in the Black Hills here. In scale and complexity, the carving would dwarf the imposing collection of presidential profiles on nearby Mount Rushmore.

As he started the Crazy Horse monument in 1947, short on money, manpower and the credulity of just about anyone who heard his plans, Korczak Ziolkowski, a sculptor from Connecticut, promised the tribal leaders who had recruited him and the local residents who scorned him that he was dedicating his life to the effort.

But he underestimated the scale of the undertaking. His promise, it turned out, was a multigenerational commitment.

The sprawling country clan Mr. Ziolkowski reared at the base of the mountain has spent the 30 years since his death honoring his final plea to continue the effort, to which he supposedly added, “But go slowly, so you do it right.”

Now led by his 85-year-old widow, Ruth, with the help of their 10 children and, more recently, their grandchildren, this eccentric family effort has plodded forward through doubts and controversy at a deliberate pace more in keeping with the age of the pyramids than the age of Twitter.

As the mountain carving effort begins its 65th year as one of the top tourist attractions in the state, few family members are deterred by their doubt that any of them will live to see it to completion.

“It’s their dream, and they’re going to get it done,” said T. Denny Sanford, a businessman and philanthropist who recently donated $10 million to the project. “I don’t care if it takes another 100 years.”

Though that commitment has been much romanticized, it has also been the focus of persistent criticism, most vocally from American Indians, who have long regarded the project with a mix of support and suspicion. Many complain that the family has made millions of dollars from a project that, while carrying the name and imagined likeness of Crazy Horse, has become more of a monument to the sculptor than to his subject.

Indeed, the bearded, mountain-man profile of Mr. Ziolkowski, who is buried on the grounds, is as ubiquitous as the stern visage of the Sioux leader around the visitor complex. And the 85 full-time staff members at the Crazy Horse Memorial Foundation included more of his descendants (seven) than Indians (five), even though the nearby reservations have some of the highest unemployment rates in the nation.

“I’ve never heard a single Native American, not one, ever say I’m proud of that mountain,” said Tim Giago, the founder of Native Sun News, based in nearby Rapid City.

Thomas Shortbull, president of Oglala Lakota College, which receives a number of scholarships from the foundation, acknowledged the discontent. “But most people see the positive of filling the void of the lack of recognition that we have in this country for Indian people,” he added.

Now grooming her children to take over, Ms. Ziolkowski, who still lives in the ascetic confines of the log cabin she helped build when she arrived here at age 20, remains the driving force behind the project that many assumed would founder when her husband died.

Instead, her focus on demonstrating progress on the mountain by completing the warrior’s face put to rest much of the persistent skepticism. Admission revenues ($3.8 million in 2010, thanks to a $10 entry fee paid by most adults) and donations ($19 million in the last five years) have reached record levels, according to the foundation.

The grandmotherly demeanor that Ms. Ziolkowski uses with strangers masks a fierce, almost obsessive dedication, family and employees said. She personally answers every phone call to the foundation, writes a thank you letter for each donation, and almost never strays out of sight of the mountain.

And while she eagerly shares her time-smoothed stories, some of which seem closer to myth than fact, she has learned from the mistake of her husband — who boldly predicted that the project would take 30 years — to remain vague when asked for a timetable for completion.

“Yes, it was bigger and harder than he thought it was going to be,” she said. “But we’ll keep working at it.”

Ms. Ziolkowski rebuffed criticism of the foundation’s relationship with Indians by pointing out that the plans — little more than a dream at this point — call for creating a university for Indians on the property. The foundation already hosts programs for Indian students and has given $1.5 million in scholarships. (Indians are not charged for admission.)

The Crazy Horse Memorial, perhaps inevitably, is usually measured against Mount Rushmore, just 17 miles away. Despite past tensions, it has served as inspiration, training ground and occasional partner.

As the presidential busts were being completed in the 1930s, local tribal leaders pushed to include some tribute to Indian heroes as well, given the location: a disputed area that was granted to local tribes by treaty, then taken back after gold was discovered. But the request to add the face of Crazy Horse alongside Washington or Lincoln was declined.

Instead they enlisted Mr. Ziolkowski, who had been fired after working briefly on Mount Rushmore. His ambitious design, measuring 563 feet tall by 641 feet long, was of a warrior with flowing hair and an outstretched arm, sitting on horseback. (Because no authenticated photograph of Crazy Horse is known to exist, there have been complaints about historical accuracy.)

Although the idea originated with Indian leaders — “this is to be entirely an Indian project under my direction,” Henry Standing Bear, a Lakota chief, wrote in a 1939 letter to the sculptor — Mr. Ziolkowski discovered after his arrival that the local tribes had little to give, either in money or labor, Ms. Ziolkowski said.

Instead, the effort was family driven, supported by donations, tourists and a small livestock operation on land they bought themselves.

After just a year in the still rugged wilderness, Mr. Ziolkowski’s first wife had filed for divorce for neglect because of his focus on the mountain. Ruth, who had known him as a teenager in Connecticut and had cut ties with her own family to follow him to South Dakota, had no such problems. They married on Thanksgiving so he would not have to take another day off.

“He was very honest,” said Ms. Ziolkowski, who had also been previously married. “He said the mountain comes first, I came second, the kids came third.”

Mount Rushmore was completed in 14 years and for less than $1 million. But here, a half-century of blasting passed before the first visible details of the face emerged. The joke for much of that period was that the only thing crazy about the Crazy Horse Memorial was the sculptor.

Standing in a biting winter wind beneath the enormous face — the nose alone is 27 feet long — Casimir Ziolkowski described the mountain carving process as not conducive to shortcuts. He started shoveling blasted rock for his father at age 7, and five decades later he is the foreman of the operation, which consumes about a quarter of the foundation’s $7 million annual budget.

He acknowledged occasional doubts about the sanity of the enterprise, but added: “Us Ziolkowskis will continue to work as long as we can.”

In addition to the jobs with the foundation, the family also owns both the gift shop and the restaurant at the visitor center. And though they donated much of their property to the foundation, they have made at least $2 million selling other parcels to it.

Jack Marsh, a longtime journalist who has served on the foundation board, dismissed financial concerns. The board had to persuade Ms. Ziolkowski, who sleeps in a chair in a room she shares with a daughter, to take a higher salary to match her workload, he said.

“The Ziolkowski family, to the person, leads modest lifestyles,” he said, “and they have truly dedicated their lives to the project.”

The most recent family addition to the staff, Heidi Ziolkowski, 26, one of the two dozen grandchildren, is now responsible for turning fragments of blasted rock into candleholders, bookends and other souvenirs. She says she is in it for the long haul, even if she, too, wonders whether she will live to see it finished.

“The older I get, the more I kind of feel like I need to be here,” she said.

Korszak Ziolkowski