[2][5] By World War II, the J. R. Simplot Company had become the largest shipper of fresh potatoes in the nation.

Simplot received an honorary degree from Utah State University in Logan in 2001,[8] honoring him for his many contributions to the agricultural industry of America, particularly the Intermountain West.

Simplot was responsible for the Potato Bust of 1976, after making massive short plays he refused to honor those contracts.

In 1995, the J.R. Simplot Company expanded into Australia, acquiring iconic food brands like Birds Eye, Leggo's, Chiko, and Edgell.

[11] Simplot's first marriage was to Ruby Rosevear (1911–2004) of Glenns Ferry,[12] whom he had met on a blind date; he proposed to her in his Model A Ford in 1931.

[13] Before his death, Simplot and his wife Esther resided in the Grove Hotel building in downtown Boise, a few blocks from the company's headquarters.

The couple donated their hilltop home, in Boise's north end, to the state of Idaho in late 2004 for use as a governor's mansion.

)[15] On January 1, 2007, while attending the Fiesta Bowl in Glendale, Arizona, with his wife and son, Simplot fell from a motorized scooter and suffered a cranial hematoma.

[17] Simplot died suddenly at his home at age 99 on May 25, 2008,[3] with his wife at his side, following a bout of pneumonia from which he appeared to be recovering.