Before the 1970s, most vehicles didn't have many emissions systems on them, but as time went on, smog pumps, charcoal canisters, and thermal reactors were added to meet new regulations.
Initially decreasing the engine compression and installing EGR systems and two way catalytic converters were able to solve this problem but later this became more difficult.
[2][3][4] This was paired with either an early version of fuel injection (typically through a Bosch Jetronic system for European vehicles)[5] or through a feedback carburetor, which had an increasing number of solenoids and settings to make sure the vehicle would emit less and less harmful emissions.
[1] Other brands would soon follow and would design different ways to tackle the same problem and would increase in complexity until they were replaced with electronic fuel injection (EFI) in the mid to late 1980s and early 1990s.
Some of the last cars with carburetors in the US include the 1994 Isuzu Pickup, 1991 Jeep Grand Wagoneer, and the 1991 Ford Crown Victoria P72.