Lawrence fell ill and collapsed on November 4, 1966, at a campaign rally held at Pittsburgh's Syria Mosque for gubernatorial candidate Milton Shapp. He was rushed to a local hospital. He died 17 days later having never regained consciousness. He was 77 years old. His death brought eulogies from both President Johnson and Truman. Funeral services were held at St. Mary of Mercy Church in downtown Pittsburgh on November 25, 1966. The 2,000 attendees included Senator Robert F. Kennedy, Mayors Joseph Barr of Pittsburgh, Jerome Cavanaugh of Detroit, James Tate and Richardson Dilworth of Philadelphia, Govs. William Scranton, James Duff, Ray Shafer and John Fine, along with President Lyndon Johnson staff members Robert Kintner and Marvin Watson, Secretary of Agriculture Orville Freeman and Secretary of the Interior Stewart Udall. After the services all guests and family joined a 250-car motorcade following the hearse down the Blvd. of the Allies, Grant Street and I-376 for the burial.