Chromosome numbers are reported for 349 individuals of 116 taxa and 2 hybrids in 13 genera from Canada and the United States. The majority of the reports are for asters listed in this paper under the generic names Symphyotrichum (93 reports) and Eurybia (51 reports) plus species of Doellingeria, Oclemena, and Sericocarpus and for goldenrods in Solidago (171 reports). Corrected identifications for four previous reports are also listed. The following are first reports for these taxa: Solidago jejunifolia, 2n = 9_II from Wisconsin; Solidago fallax var. molina, 2n = 18 from Québec; and Symphyotrichum falcatum subsp. falcatum, 2n = 10 from Northwest Territories. Multiple counts are first reports for a particular taxon in a province or state: e.g., Solidago salicina, 2n = 18 from North Carolina; Symphyotrichum grandiflorum, 2n = 60 from Virginia; and Symphyotrichum welshii, 2n = 16 from Wyoming. The following are all first reports for the province of Prince Edward Island: Solidago nemoralis subsp. nemoralis, 2n = 18; Symphyotrichum lanceolatum var. lanceolatum, 2n = 64, Symphyotrichum puniceum var. puniceum, 2n = 16.