Hematopoietic stem cells (HSCs) reside in a perivascular niche but the location remains controversial 1 . HSCs are rare and few can be found in thin tissue sections 2, 3 or upon live imaging 4 , making it difficult to comprehensively localize dividing and non-dividing HSCs. We discovered that α-catulin GFP/+ was expressed by only 0.02% of bone marrow hematopoietic cells, including virtually all HSCs. One in 3.5 α-catulin-GFP +c-kit + cells gave long-term multilineage reconstitution of irradiated mice, indicating that α-catulin-GFP +c-kit + cells contain HSCs with a purity comparable to the best markers available. We were able to optically clear the bone marrow to perform deep confocal imaging, making it possible to image thousands of α-catulin-GFP +c-kit + cells and to digitally reconstruct large segments of bone marrow. The distribution of α-catulin-GFP +c-kit + cells indicated that HSCs were more common in central marrow than near bone surfaces and in the diaphysis relative to the metaphysis. Nearly all HSCs contacted Leptin Receptor + and Cxcl12 high niche cells. Approximately 85% of HSCs were within 10μm of a sinusoidal blood vessel. Most HSCs were distant from arterioles, transition zone vessels, and bone surfaces. This was true of Ki-67 + dividing HSCs and Ki-67 − non-dividing HSCs. Dividing and non-dividing HSCs thus reside mainly in perisinusoidal niches with Leptin Receptor +Cxcl12 high cells throughout the bone marrow.