In early telephone systems,connections were made in the central office bytelephone operators usingpatch cords to connect one party to another. If a person wanted to make a phone call,he or she would pick up a phone and wind a crank on the side. The crank was a small generator that would light a lamp at the central office. An operator would see the light and insert their patch cord into a socket and assist the customer with the call connection. The operator would use patch cords to connect the caller to the person being called. If the party being called was in another exchange,the operator would use a patch cord to connect to another exchange where an operator elsewhere would finish the connection. As technology advanced,electro-mechanical switches were introduced and calls were made usingrotary dials.Initial use of area codes in the United States began in the 1950s with large cities. By 1966,the system was nationwide. Area codes were assigned based on the length of time arotary dial phone took to dial the area code. Densely populated areas like New York City,Chicago,Los Angeles,and Detroit had huge incoming call volume and were assigned numbers (212,312,213,313) that could be quickly dialed from a rotary dial phone. On a rotary dial phone low digits (1,2,3,4) could dial quickly as the time the rotary dial took to return to the home position was minimal. High digit numbers (7,8,9,0) on rotary dial phones took much longer to return to the home position and were usually used in less densely populated areas like rural Texas (915). This numbering strategy became unnecessary whentouch-tone phones arrived,as the tone allowed instant entry of digits.