The first "Crown Victoria" appeared in 1955; it was a 2-door 6-seater hardtop coupe, part of the Ford Fairlane range, that differed from the regular Victoria model by having a lower, sleeker roofline and much more stainless steel trim, incuding a stainless steel band that 'crowned' the roofline, passing right over the car, as an extension of the B-pillar line. That model did not outlast the 1950s.
In 1979, Ford brought back the name on a deluxe version of the LTD full-size car line. It was recognizeable by its four headlights with amber turn signals beneath them (base LTDs had two headlights, and clear turn signals in the grille). There was a 2-door coupe (all steel top this time), 4 door sedan and a wagon- the wagon became a "Country Squire" if fake-wood trim was ordered. Most had 5.0L V8s, all had automatics.
By 1982 the LTD designation was dropped along with the base model. The coupe did not last past 1985. In 1992 the sedan body (production of the [station wagon] having ceased in 1991) was completely redesigned to the round, six-window shape, and there was a new 4.6L "Triton" engine. There was a further facelift in 1998 and chassis modifications for 2002.
This car, its slightly more luxurious twin the Mercury Grand Marquis, and the more expensive Lincoln Town Car are just about the only mass-produced passenger cars left in the world with a fully separate chassis as opposed to the more modern "unibody" contruction style where the body panels are load bearing members.
Some 90% of police cars in the US and Canada are Crown Victorias. Current and former police versions (the latter are often used as taxis) handily outnumber civilian models.
There has been some controversy and lawsuits in recent years over the car's tendency to explode when rear-ended due to its retention of the gas tank in the once-industry-standard position of behind the rear axle, rather than the now more common location of in front of the rear axle. The condition was exacerbated by the positioning of a sharp bolt on the rear axle, which would puncture the tank in certain types of accidents. Measures have been taken to correct the worst of the problem.