George M. Leader, who was elected governor of Pennsylvania at age 37, died May 9 at his home at an assisted living facility in Hershey, Pa. He was 95.

Kelly S. Kuntz, a spokeswoman for the Country Meadows assisted living center, confirmed the death. The cause was not disclosed.

Mr. Leader, a Democrat, took office as governor in 1955 and served one four-year term, the maximum allowed by law at the time. He was the second-youngest person to be elected Pennsylvania’s governor.

He fought to rid government of patronage jobs and improve social services. Under his leadership, the state overhauled its mental health system and made special education a requirement in schools. He was the first Pennsylvania governor to appoint an African American to his cabinet.

Mr. Leader served in the state Senate from 1951 to 1954, succeeding his father. He was widely expected to lose the 1954 gubernatorial election, but he used the new medium of television to gain a sizable edge over his rival, Lt. Gov. Lloyd Wood.

This photo from the Pennsylvania State Department of Commerce shows George Leader, left in suit, campaigninga. Leader, who rose from his parents' chicken farm to become governor in 1955, died May 9, 2013. He was 95. (Uncredited/AP)

Mr. Leader ended his political career after losing a bid for U.S. Senate to Republican Hugh Scott in 1958. He spent the subsequent decades running a chain of assisted living businesses and fighting for causes such as prison reform.

George Michael Leader was born in York County, in south-central Pennsylvania, on Jan. 17, 1918. He grew up on his family’s poultry farm and attended a one-room schoolhouse and later Gettysburg College.

In 1939, he married Mary Jane Strickler. She died in 2011.

Mr. Leader served aboard the aircraft carrier USS Randolph during World War II. When the war ended, he returned to York County and used a GI loan to buy a 110-acre farm.