One in four active Ile-de-France residents changes their mode of travel during the week. What was the impact of the health crisis and what lessons can we learn from it to adapt public policies? The Paris Region Institute carried out its first GPS mobility survey (EMG) Commissioned by a public-private consortium bringing together 14 partners including the region and the Ile de France transport authority (IDFM), the City of Paris, the four departments of the greater suburbs and operators, such as RATP or SNCF.