Census flow data involve flows of individuals in the UK between origins and destinations. These flows are either the residential migrations of individuals from one place of usual residence to another, or of commuters making journeys from home to workplace. These data are derived from the questions on the census form relating to usual place of residence one year ago, and the place of work for the respondent's main job. The Web-based Interface to Census Interaction Data (WICID) Flow Data service facilitates access to Census interaction data for members of UK higher and further education institutions. The 1991 datasets currently held include: Census migration datasets: 1991 Census: Special Migration Statistics (Sets 1, including re-estimation for 2001 boundaries, and 2, MIGPOP, SMSGAPS and SAS LBS Table 100 A and B); Migration data at Ward and District level; Ward-level re-estimations for 2001 geographies. Census commuting datasets: 1991 Census: Special Workplace Statistics (Sets A, B and C - including modified set Cs); Commuting data by residence (A), Workplace (B), and within and between wards (C) for 1991 and 2001 boundaries.