The immune system ages with our body and so does the hematopoietic stem cell (HSC) pool that creates it. Upon ageing, HSC, like other stem cells, are though to decline in their regenerative capacity. Mostly studied post-transplantation, it remains unclear how HSCs age in the native niche. To address this issue, we developed a novel in situ single cell lineage tracing technology to elucidate the clonal composition and cell production of HSCs in their natural niche upon ageing. Our results demonstrate that a large pool of stem cells with unequal output maintains myelopoiesis through overlapping waves of cell production. We describe how the increase in myeloid cell production with age occurs through an increase in the number of active HSCs, rather than increased cellular output of individual HSC. These results suggest that there is no functional decline of HSC with age. The immune system ages with our body and so does the hematopoietic stem cell (HSC) pool that creates it. Upon ageing, HSC, like other stem cells, are though to decline in their regenerative capacity. Mostly studied post-transplantation, it remains unclear how HSCs age in the native niche. To address this issue, we developed a novel in situ single cell lineage tracing technology to elucidate the clonal composition and cell production of HSCs in their natural niche upon ageing. Our results demonstrate that a large pool of stem cells with unequal output maintains myelopoiesis through overlapping waves of cell production. We describe how the increase in myeloid cell production with age occurs through an increase in the number of active HSCs, rather than increased cellular output of individual HSC. These results suggest that there is no functional decline of HSC with age.