Most of the amalgamations took place in 1967 and the municipality in its present form was created in 1971.

There are 30 original local government units within the present municipality.

As of 2018, there were 17 localities in the municipality:[3] This is a demographic table based on Västerås Municipality's electoral districts in the 2022 Swedish general election sourced from SVT's election platform, in turn taken from SCB official statistics.

[4] In total there were 156,510 residents, including 116,663 Swedish citizens of voting age.

This made Västerås the most populated municipality in which the right coalition won the vote.