The strip mill was a major innovation, with the first being erected at Ashland, Kentucky in 1923. This provided a continuous process, cutting out the need to pass the plates over the rolls and to double them. At the end the strip was cut with a guillotine shear or rolled into a coil. Early (hot rolling) strip mills did not produce strip suitable for tinplate, but in 1929 cold rolling began to be used reduce the gauge further. The first strip mill in Great Britain was opened at Ebbw Vale in 1983 with an annual output of 200,000 tons.

The strip mill had several advantages over pack mills:

It was cheaper due to having all parts of the process, starting with blast furnaces on the same site.

Softer steel could be used.

Larger sheets could be produced at lower cost and this reduced cost and enabled tinplate and steel sheet to be used for more purposes.

It was capital intensive, rather than labour intensive.