Tropical Cyclone Tracy struck Darwin in the early hours of 25 December 1974; Tracy was rated Category 4. Before the instruments failed, wind gauges registered speeds of 217 kilometres per hour. 

The damage to buildings and infrastructure was massive; Tracy impacted all power, water, sanitation and communications. Both commercial and industrial losses were huge. Over 80 per cent of all buildings were either destroyed or left seriously damaged. 

The cyclone resulted in the deaths of 71 people; these included 22 who were lost at sea.

Cyclone Tracy caused the largest ever evacuation and reconstruction operations in peacetime Australia. A total of 35,362 people (of the approx 47,000 population) were evacuated to southern cities for many months:

• 25,628 by air
  • 15,950 in civilian aircraft
  • 9,678 in military aircraft
• 9734 by road.
  

By 1978, Darwin was estimated to have regained the population level it had in December 1974.

The Insurance Council of Australia estimated the 1974 damage at $200 million, with the 2012 estimated normalised cost of $4090 million.