We conducted aerial surveys to locate radio-marked Canada geese (Branta canadensis interior) during May-June 1984-86 throughout the presumed breeding grounds of the Mississippi Valley population (MVP). Based on 84 adult females located, 84 8(CI)% nested <80 km from the coasts of the Hudson and James bays. Similarity of breeding ground distributions suggest geese in the MVP that are associated with fall staging in Wisconsin and southern Illinois, specific refuges in southern Illinois, or roosting sites within refuges, do not constitute subpopulations with discrete breeding distributions. J. WILDL. MANAGE. 52(4):689-693 The breeding range of geese in the MVP has been described by Hanson and Smith (1950), Vaught and Arthur (1965), and Reeves et al. (1968). Malecki et al. (1980) and Craven and Rusch (1983) defined the northwestern boundary as near York Factory, Manitoba. Recent data from summer banding indicate the southeastern boundary of the MVP breeding range is near the Albany River in Ontario (H. G. Lumsden, Ont. Minist. Nat. Resour., pers. commun.). The distribution of geese in the MVP within these boundaries is poorly documented. Canada geese are managed on the basis of populations; e.g., the MVP (Bellrose 1980). However, results of studies have suggested that the MVP has manageable subunits (Raveling 1969, Kennedy and Arthur 1974, Anderson and Joyner 1985:422) that may occupy distinct areas within the general breeding range. Identification of subunits would facilitate improved harvest management and reduce potential for overharvest of some genetic groups (Raveling 1969, Kennedy and Arthur 1974). Kennedy and Arthur (1974) suggested the possibility of separate breeding distributions for early and late migrants to southern Illinois, and for early migrants using different refuges in southern Illinois. Raveling (1969) believed that subflocks existed among geese in the MVP at Crab Orchard National Wildlife Refuge (NWR), and that these probably used different nesting areas. Our objectives were to define the breeding distribution of Canada geese in the MVP, and to compare distributions of early and late migrants to southern Illinois, early migrants using different refuges in southern Illinois, and different roost areas at Crab Orchard NWR. We thank D. D. Thornburg and K. F. Abraham for assistance throughout the study. Personnel from Horicon NWR, Crab Orchard NWR, and Union County Refuge assisted with trapping and banding efforts. Logistical support was provided by the Moosonee and Sioux Lookout Districts of the Ontario Ministry of Natural Resources. Aerial surveys were assisted by T. K. W dling and other pilots of the Air Institute, Sout rn Illinois University at Carbondale. D. W. Brewer, D. F. Caithamer, and R. J. Gates provided valuable field assistance. D. D. Thornburg reviewed the manuscript. This study was funded by the Illinois Department of Conservation, Federal Aid to Wildlife Restoration Project W-95-R(SI).