The modern founders of the town are considered to be the member of Parliament, Peter Tonning, and the fish exporter Carl Rønneberg. They ensured that Ålesund was given rights to trade and export without going through Bergen. Because of this, Ålesunds growth coincides with Bergen’s decline.

Thanks to the natural harbour, Ålesund grew very quickly. The nearby rich fisheries and the harbour brought people from all over the west. Eventually fish processing factories were established, and the expanding fishing fleet grew here as well. Eventually steamships began docking at Ålesund and larger factories were built.

In 1872, author Magdalene Thoresen described the city as follows:

It is a fresh sight to see this small coastal town with its newly built houses, scattered over the bare mounds that often look like reefs, and you get the impression that it was built in a hurry, built up by chance and the mood which comes with a fast, dangerous profession. Here, no even, calm deliberation goes through anything; even the large, dizzying warehouses and individual magnificent buildings speak only of the rapid rise of profit and the boldness of large speculations. Of course, there are also buildings which clearly show that here prosperity resides in safe enclosure, here no more daring. But most of it gives the impression of rapid rise

Ålesund continued to experience wealth and rapid growth until the fire of 1904 struck.