During his lifetime, Gilcrease collected more than 10,000 artworks, 250,000 Native American artifacts and 100,000 rare books and documents, including the only surviving certified copy of the Declaration of Independence.

[2] Gilcrease attended Bacone College, where his most influential teacher was Alexander Posey,[a] who taught his students the arts, sciences, writing, and about their American Indian heritage.

[2] At the turn of the 20th century, the federal government dissolved the Indian Nations land by distributing parcels into private ownership.

At age nine, Gilcrease's 1/8 Creek heritage entitled him to receive 160 acres (650,000 m²), located about twenty miles (32 km) southwest of Tulsa, Oklahoma.

His land, sitting astride the huge Glenn Pool Oil Reserve, made Gilcrease a multi-millionaire by the time he was twenty.

[2] He fathered two sons with Belle: William Thomas Gilcrease, Jr., who was born on July 23, 1909, in Oklahoma and died on March 16, 1967, in Nacogdoches, Nacogdoches County, Texas, and Barton Eugene Gilcrease, who was born on April 12, 1911, in Tulsa, Oklahoma, and died on September 25, 1991, in San Antonio, Bexar County, Texas.

[4] Initially, the divorce provided for $72,000 alimony, payable at the rate of $200 per month, but with a provision that all payments would cease if Norma were to remarry.

In 1946, Gilcrease was honored by the Sioux Nation, made an honorary tribal member and given the name Wicarpi Wakatuya, which means "High Star".

Although his oil income was not insubstantial, major collection purchases limited his cash flow and placed him in a position of being unable to meet his current debt.

Swift action by the people of Tulsa enabled the debt to be covered by a local bond issue, and the collection remained in Oklahoma.

At a time when few were interested in Native American or Western painting and sculptor, Gilcrease supported a number of Oklahoma artists, including Woody Crumbo (Potawatomi) and Acee Blue Eagle (Muscogee Creek) and Willard Stone, each of whom created works held in the collection.

The rock home, dating from approximately 1912, had been extensively remodeled over the years and was surrounded by a garden specializing in plants used by local tribes.

In addition, Gilcrease committed oil property revenue to Tulsa for museum maintenance until the bond was fully repaid.

Gilcrease's funeral was conducted in a manner that honored his Native heritage, with Chief Wolf Robe Hunt of the Acoma Pueblo in New Mexico leading the prayer.