Technology & Medicine › Electric age › Internal combustion engine and the car
Moving assembly line (Ford)
December 1913 (Highland Park)· Invention or discovery· Tools, energy & materials
Well documentedSolid records, physical evidence or scientific consensus.
Ford's system of moving the work past stationary workers, each doing one task, which cut Model T chassis assembly from about 12.5 hours to 1.5.
See it on the Technology & Medicine map →How it works
Henry Ford's engineers at the Highland Park plant near Detroit combined interchangeable parts, specialized machine tools and conveyors, borrowing ideas from meatpackers' 'disassembly' lines. In late 1913 the chassis began moving on a rope, then a chain, past workers. Assembly time fell from about 12.5 hours to about 1.5. The Model T's price dropped from $850 in 1908 to under $300 by the mid-1920s. To curb high worker turnover, Ford roughly doubled pay to $5 a day in 1914.
Why it mattered
Mass production made cars and later appliances affordable to ordinary workers, and its methods spread to nearly every industry; the repetitive work also fueled labor unrest and unions.
Think of it like
Like a production homebuilder's crews moving lot to lot, each doing one trade, except here the house moves past the crews.
How we know
Ford Motor Company records and time studies at the Benson Ford Research Center in Dearborn; contemporary accounts such as Arnold and Faurote's 1915 book 'Ford Methods and the Ford Shops'.
Still unknown or debated
Credit is shared among Ford engineers such as Charles Sorensen, Clarence Avery and William Klann; how much they drew on meatpackers, gunmakers and Ransom Olds's earlier line is debated.
Connections (3)
▸Factories and the factory system were streamlined into the Moving assembly line (Ford)Well documented
The connection
The factory system gathered workers and machines under one roof and split work into steps. Ford's line pushed that logic further: interchangeable parts, machines placed in process order, and the work itself moving on a conveyor at a set pace, so the line, not the worker, set the speed.
When and how
From Arkwright's Cromford Mill in England (1771) and the 'American system' of interchangeable parts at US armories, to Ford's Highland Park plant in Michigan, 1913.
How we know
Ford's engineers and 1910s trade journals described what they borrowed from earlier factories, armories and meatpacking plants; plant layouts show the step-by-step evolution.
Debates and open questions
Historian David Hounshell and others debate how truly interchangeable earlier 'American system' parts were, and so how new Ford's precision really was.
▸Electric power and the grid drove the motors of the Moving assembly line (Ford)Mostly agreed
The connection
Steam-powered factories ran machines from one engine through long line shafts and belts, which dictated the layout. Electric motors on each machine let Ford place machines in the order the work flowed, not around a shaft. Highland Park was built for electricity from the start, and motors drove its conveyors and chains.
When and how
Highland Park, Michigan, opened in 1910 with its own power plant; moving lines from 1913. Individual motor drives spread through US factories from about 1900 to 1930.
How sure are we?
Ford plant records and engineering accounts describe the electric drives; economist Paul David's studies trace how electric motors reshaped factory layouts.
Debates and open questions
How much the line depended on electric drive, versus simple conveyors and management methods, is a matter of emphasis among historians.
▸Internal combustion engine and the car was mass-produced on the Moving assembly line (Ford)Well documented
The connection
The Model T, launched in 1908, was simple, tough and designed to be built in huge numbers from interchangeable parts. Demand outran Ford's workshops, so his engineers developed the moving line to build it faster. Output rose from under 200,000 cars in 1913 to about 2 million in 1923; over 15 million were made by 1927.
When and how
Ford's Highland Park plant near Detroit; a moving line for flywheel magnetos in April 1913, then the full chassis line by early 1914.
How we know
Ford production records and time studies at the Benson Ford Research Center document each step, with falling assembly times and prices.
Debates and open questions
Whether Ford's $5 day was mainly about cutting worker turnover or about creating customers who could afford cars is debated.