SUVs first became popular in the late '80s and early '90s, when the success of the Jeep Cherokee and the Ford Explorer started an arms race to see who could make the largest possible SUV that they could get away with. While the SUV by itself dates back to the late 1940s, and luxurious models were marketed as early as the 1960s, it took a few decades of technological evolution to "civilize" them — few non-professional people would feel at home with the complex mechanical transmissions, rigid axles, poor balance, and slow highway speed of earlier samples. By around the Turn of the Millennium this became a self-fulfilling trope, with car buyers recommended to buy larger vehicles just so that they wouldn't get squashed if they got in a car accident. It rapidly became a Discredited Trope late in the Aughts due to the rise in gas prices and concerns over safety (specifically rollovers), though the 15-20 year lifespan of the typical motor vehicle means they're still not an uncommon sight on the road.
Another big reason for the popularity of this kind of car is the quirks in the US' Corporate Average Fuel Economy (CAFE) regulation. After the OPEC oil embargo of 1973 caught domestic manufacturers completely flat-footed with nothing but big gas-guzzling cars to sell as fuel prices rose, the federal government saw the resulting economic damage and instituted CAFE standards to encourage the manufacture and sale of more fuel-efficient vehicles.
While well-meaning, this system had a major loophole. CAFE had exemptions for "light trucks", defined as such:
- "Light-duty truck means any motor vehicle rated at 8,500 pounds GVWR or less which has a vehicle curb weight of 6,000 pounds or less and which has a basic vehicle frontal area of 45 square feet or less, which is: (1) Designed primarily for purposes of transportation of property or is a derivation of such a vehicle, or (2) Designed primarily for transportation of persons and has a capacity of more than 12 persons, or (3) Available with special features enabling off-street or off-highway operation and use."
In short, these vehicles were intended to allow working professionals who needed more heavily-built vehicles to still be able to purchase them. However, CAFE's definition of "utility" was very broad, allowing automakers to effectively build giant station wagons and market them as light trucks. Probably the most egregious instance of this gaming of regulations was the Chrysler PT Cruiser, a retraux station wagon built on the same platform as the Neon compact that was engineered such that it was technically classified as a light truck. The PT Cruiser averaged 19 miles per gallon in city driving and 24 in highway driving, a gas-guzzler for something of its size and weight; classifying it as a light truck not only improved the CAFE rankings of Chrysler's truck lineup, it also kept the car from dragging down the CAFE rankings of Chrysler's car lineup. This may be one of the reasons why it remained in production, virtually unchanged, from 2000 until 2010 despite seeing its sales collapse after 2006. Closing this loophole and tightening the definition of "utility" has, needless to say, been a major goal of American environmentalists.