A distinction must be made between Miramas-le-Vieux, the original village, and Miramas, a town of around 27,500 inhabitants which extends a few kilometers from the old village, located between Arles and Aix-en-Provence, and which is experiencing a new economic boom.
The territory of the commune is located north of the Etang de Berre, about 60 km north-west of Marseille.
The development of the railways is accompanied by an economic boom in Miramas and neighboring municipalities.
In 1923, the Army set up a warehouse area in place of the airfield (becoming the Miramas General Ammunition Reserve Warehouse).