How did the growth of automobiles increase the demand for lead in the 20th century?

The growth of the automobile industry in the 20th century significantly increased the global demand for lead through two primary applications:

• Lead-Acid Batteries: The rise of the automobile created a massive market for storage batteries, which are essential for starting, lighting, and ignition systems in vehicles. These batteries eventually consumed approximately 75 percent of the world’s lead production. The steady increase in the number of internal-combustion engines directly fueled the rising production of these lead-acid units.12
• Gasoline Additives: In 1921, tetraethyl lead was introduced as a gasoline additive to solve "knocking" problems in high-compression engines. Despite the known health risks, it became the standard antiknock agent for automotive fuel for much of the 20th century.13

The use of lead in gasoline eventually declined following the introduction of catalytic converters in the 1970s, as lead interfered with these pollution-control devices, leading to the global phase-out of leaded gasoline.13