The range of Astragalus neglectus is centred around the Great Lakes, but it also occurs from Manitoba and South Dakota east to Massachusetts and Virginia. It is rare throughout most of its range. It is found in wet to dry, open, often rocky habitats, especially those that are calcareous. Natural disturbance is required to maintain these open habitats.
Conservation
Although ranked globally as apparently secure, this species is considered to be a rare and potentially vulnerable species within most of the states and provinces where it occurs. It is classified as endangered in Wisconsin. It was formerly considered to be at risk in Minnesota but was delisted after the discovery of numerous new populations in the 1990s.