As major airlines are in the midst of one of the largest fleet modernization programs in history, the B-757 continues to be a very popular aircraft even with the delivery of brand new planes to service similar routes. The 757 was in production from 1981 to 2004, with approximately 1,000 deliveries over that time period. The plane was designed with two variants - the 200 and 300 models (max capacities of 240 and 290 people in one-class configurations, respectively). The 200 model also had two variants (the SF and PF), which were both designed as cargo-only planes.
The general longevity of these aircraft is likely hidden right below the wings. The 757 was outfitted with either a set of P&W-2037 or RR-RB211 engines. The P&W variant is slightly less powerful than the RR version, putting out roughly 38,400lbs of maximum thrust. The RR version has a maximum thrust output of a whopping 40,100lbs. In any case, both engine variants make the 757 the most powerful commercial aircraft in the world, in terms of power-to-weight ratio. It has been rumored that a fully-loaded 757-200 (cargo, passengers, and fuel) can take off with less than 5,000 feet of runway. This is quite remarkable when compared to a B-777-200ER, which at full-capacity, needs approximately 8,000 feet of runway - about 60% more asphalt than the 757.
Due to its power, the 757 rarely (if ever) uses the engines' full capacity - leading to greater fuel efficiency and less maintenance. Additionally, whereas other aircraft like the 737 can be grounded by hot weather and weight restrictions, the 757 does not face any such constraints based on its ability to climb off the runway like a rocket-ship (literally).
Additionally, the range of the 757 also contributes to its unique value to a fleet with the 200 variant maxing out at a range of 3,900 nautical miles, which converts to approximately 4,500 miles. This range makes it one of the only non wide-body commercial aircraft capable of transatlantic flights. Although after a flight from New York to Ireland on a 757 in coach, I will be the first to say that it's not a comfortable experience.
The 757 is still going strong 32 years after the first deliveries were made. It continues to be a mainstay within the fleets of all of the major U.S. airlines. The unique engineering and design decisions have brought a greater appreciation to this iconic aircraft.