In 1964 he challenged the remnants of the Tom Pendergast political machine in the race for governor.
During the primary he campaigned against Kansas City establishment candidate Hilary A. Bush charging, "At one time all Missouri was controlled from Kansas City by a man named Pendergast.
This type of machine politics should never be allowed to rear its ugly head again in Missouri politics."
Among Hearnes' planks was an effort to gain support in western Missouri by the establishment of a four-year college (Missouri Western State University) in the population center of St. Joseph, Missouri despite the presence of a state college (Northwest Missouri State University) less than 50 miles away in the much smaller city of Maryville, Missouri.

Hearnes also campaigned against the Central Trust Bank of Jefferson City, Missouri (which, since its 1902 founding by Lon Stephens, had been the central depository for state funds), saying that the bank's power was creating an atmosphere where establishment forces would "select rather than elect" a leader.

Hearnes won the primary over Bush with 51.9% of the vote.
He won by more than 500,000 votes and 62% of the vote, defeating Republican Washington University in St. Louis chancellor Ethan A.H. Shepley.
His lieutenant governor in the race was Thomas Eagleton.
In 1965 the constitution was amended to permit governors to succeed themselves to serve two terms.

He was re-elected in 1968.
He defeated Lawrence K. Roos, former St. Louis County Executive and former president of the St. Louis Federal Reserve Bank.
He had 60.8% of the vote.

Hearnes' priorities as Governor included improving public education, bettering the state's highways and traffic safety, as well as civil rights and the environment.
State aid to public schools increased from $145.5 million to $389.2 million during Hearnes' term as governor, an increase of 167%, and he also increased state aid to higher education from $47.5 million to $144.7 million, an increase of 204%.

He oversaw the increase of state aid to vocational education from $856,000 to $8.8 million, fostering the establishment 53 new area vocational educational schools.
While Hearnes was Governor, the State of Missouri built 350 miles of four-lane highways throughout the state.
He also created the Missouri Division of Highway Safety and enacted a law providing mandatory breath tests for suspected drunken drivers.
Hearnes increased uniform strength of the Missouri State Highway Patrol from 500 to 750 officers.

Hearnes was Governor during the Civil Rights era and as Governor he signed a Public Accommodations Law, Missouri's first civil rights act.
As governor he also strengthened the Fair Employment Practices Act and increased the staff of the Human Rights Commission from two employees to 35.
Hearnes also enacted the state's first air pollution law, with subsequent strengthening of its provisions.
He oversaw the passage of a $150 million water pollution bond issue to provide state matching funds for sewage control construction projects, and created the state's Clean Water Commission to enforce water pollution laws.
He also was responsible for the provision of first state financial grants for mass transit and urban rapid transit facilities.
He created the Department of Community Affairs to assist local governments in obtaining technical assistance and grants for city planning, zoning, housing, sewage treatment, industrial development, and other municipal and regional projects.

In 1970, he was elected chairman of the National Governor's Association which held its annual conference at Lake of the Ozarks.
In 1972, he supported Edmund Muskie for President and was considered a possible running mate, had Muskie won the nomination.
In 1964 he challenged the remnants of the Tom Pendergast political machine in the race for governor. During the primary he campaigned against Kansas City establishment candidate Hilary A. Bush charging, "At one time all Missouri was controlled from Kansas City by a man named Pendergast. This type of machine politics should never be allowed to rear its ugly head again in Missouri politics." Among Hearnes' planks was an effort to gain support in western Missouri by the establishment of a four-year college (Missouri Western State University) in the population center of St. Joseph, Missouri despite the presence of a state college (Northwest Missouri State University) less than 50 miles away in the much smaller city of Maryville, Missouri.
Hearnes also campaigned against the Central Trust Bank of Jefferson City, Missouri (which, since its 1902 founding by Lon Stephens, had been the central depository for state funds), saying that the bank's power was creating an atmosphere where establishment forces would "select rather than elect" a leader.
Hearnes won the primary over Bush with 51.9% of the vote. He won by more than 500,000 votes and 62% of the vote, defeating Republican Washington University in St. Louis chancellor Ethan A.H. Shepley. His lieutenant governor in the race was Thomas Eagleton. In 1965 the constitution was amended to permit governors to succeed themselves to serve two terms. 
He was re-elected in 1968. He defeated Lawrence K. Roos, former St. Louis County Executive and former president of the St. Louis Federal Reserve Bank. He had 60.8% of the vote.
Hearnes' priorities as Governor included improving public education, bettering the state's highways and traffic safety, as well as civil rights and the environment. State aid to public schools increased from $145.5 million to $389.2 million during Hearnes' term as governor, an increase of 167%, and he also increased state aid to higher education from $47.5 million to $144.7 million, an increase of 204%. 
He oversaw the increase of state aid to vocational education from $856,000 to $8.8 million, fostering the establishment 53 new area vocational educational schools. While Hearnes was Governor, the State of Missouri built 350 miles of four-lane highways throughout the state. He also created the Missouri Division of Highway Safety and enacted a law providing mandatory breath tests for suspected drunken drivers. Hearnes increased uniform strength of the Missouri State Highway Patrol from 500 to 750 officers.
Hearnes was Governor during the Civil Rights era and as Governor he signed a Public Accommodations Law, Missouri's first civil rights act. As governor he also strengthened the Fair Employment Practices Act and increased the staff of the Human Rights Commission from two employees to 35. Hearnes also enacted the state's first air pollution law, with subsequent strengthening of its provisions. He oversaw the passage of a $150 million water pollution bond issue to provide state matching funds for sewage control construction projects, and created the state's Clean Water Commission to enforce water pollution laws. He also was responsible for the provision of first state financial grants for mass transit and urban rapid transit facilities. He created the Department of Community Affairs to assist local governments in obtaining technical assistance and grants for city planning, zoning, housing, sewage treatment, industrial development, and other municipal and regional projects.
In 1970, he was elected chairman of the National Governor's Association which held its annual conference at Lake of the Ozarks. In 1972, he supported Edmund Muskie for President and was considered a possible running mate, had Muskie won the nomination.
Warren E. Hearnes