the Edmonton municipal government and became the commercial Edmonton City Centre (Blatchford Field) Airport. During this period, in about 1942, the aerodrome was listed at with a Var. 25 degrees E and elevation of . The facility was listed as being a Department of Transport and RCAF Aerodrome and had three runways, listed as follows: Weather A weather station was established in 1937. Over the years since then, its site witnessed increasing influence by the urban heat island effect. By the mid-1970s, "Edmonton Municipal A." (as it was listed in the Monthly Record of Meteorological Observations in Canada) was regularly recording some of the longest frost-free periods in the Prairie Provinces, with the first fall frost often not coming before October. Scheduled passenger service 1950s and 1960s In 1950, the airport was a stop on an international route operated by Northwest Airlines between the U.S. and Asia. According to the September 24, 1950, Northwest Airlines system timetable, the air carrier was operating Douglas DC-4 propliner service on a routing of New York City - Washington, D.C. - Chicago - Minneapolis/St. Paul - Edmonton - Anchorage - Tokyo four days a week with continuing service to Okinawa and Manila or Taipei depending on the day of the week. By the late 1950s, three Canadian-based airlines were providing primary scheduled passenger air service at the airport: major air carriers Canadian Pacific Air Lines (which would become CP Air) and Trans-Canada Air Lines (TCA, which would become Air Canada) as well as regional air carrier Pacific Western Airlines (PWA). In 1959, Canadian Pacific was operating international service to Europe with four nonstop flights a week flown with Douglas DC-6B "Empress" propliners between Edmonton and Amsterdam with these flights originating and terminating in Vancouver and was also operating local domestic service with Convair 240 prop aircraft to Grande Prairie, Alberta and Fort St. John, British Columbia. A year earlier in 1958, Trans-Canada was flying Lockheed L-1049 Super Constellation and Canadair North Star (a Canadian produced version of the Douglas DC-4) propliners in addition to Vickers Viscount turboprops on nonstop services to Vancouver, Toronto, Winnipeg and Saskatoon as well as direct, no change of plane flights to Montreal. According to the June 1, 1958, Trans-Canada Air Lines system timetable, the air carrier was also operating five nonstop departures a day to Calgary with Viscount propjets. Pacific Western was operating regional services from the airport in