The rapid growth of telephone service demand, especially after World War II, resulted in a large fraction of party line installations in the middle of the 20th century in the United States. This often led to traffic congestion in the telephone network, as the line to a destination telephone was often busy. Nearly three-quarters of Pennsylvania residential service in 1943 was party line, with users encouraged to limit calls to five minutes. Shortages persisted for years after each war; individual lines in Montreal remained in short supply at the end of 1919 and similar shortages were reported by telephone companies in Florida as late as 1948. Some rural users had to run their own wires to reach the utility's lines.