Arvey assumed the position of Chairman of the organization after Kelly's ouster in 1947. Arvey put reformers on the slate, such as Martin H. Kennelly for mayor, Paul Douglas for United States Senate, and Adlai Stevenson for governor of Illinois. During the early years of the 1950s, Joseph L. Gill – George Brennan's brother-in-law – replaced Arvey as Chairman of the party. His role was more of a caretaker than that of a political leader. Under Richard J. Daley The Democratic committeemen of Cook County elected Richard J. Daley as their chairman in 1953 and the Democratic committeemen of Chicago slated him as their mayoral candidate in 1955. He served as chairman for 22 years and as mayor for twenty years. This was accomplished with the help and support of William L. Dawson. In return, an African-American "sub-machine" led by Dawson was created under the umbrella of the regular machine. In the predominantly African-American wards, Dawson was able to act as his own political boss. He amassed a considerable power base by awarding political appointments to his allies, just as Daley did in the larger machine. However, Dawson's machine had to continually support the regular machine in order to retain its own clout. Daley helped turn out the vote for John F. Kennedy in the 1960 presidential election. Kennedy won Illinois by 9,000 votes, yet won Cook County by 450,000 votes, with some Chicago precincts going to Kennedy by over 10 to 1 margins. Illinois' 27 electoral votes helped give Kennedy the majority he needed. Chicago was selected to host the 1968 Democratic National Convention. Political commentator Len O'Connor described this period as Richard J. Daley's "High Water Mark" and described the Cook County Democratic Party at the time as one of the most powerful political machines in American history. Under George Dunne and Edward Vrdolyak The Shakman Decrees introduced judicial oversight of City and County hiring, reducing the number of voters who owed their livelihoods to the Democratic party. The 1968 convention had ended in disaster. The Walker Report concluded that a "police riot" had taken place at the 1968 Democratic National Convention in Chicago. NBC News had televised the event and switched back and forth between demonstrators being beaten by the police in front of the convention hall and the festivities over Humphrey's victory inside. Racial tension over issues such as urban renewal in Woodlawn and Lincoln Park,