The introduced tropical milkweed species A. curassavica is an almost year-round stable food source for monarch butterflies in the United States that may contribute to growing non-migratory populations. Resident monarch populations seem to have higher levels of Ophryocystis elektroscirrha (OE), a protozoan parasite, which does not clear in non-migratory monarchs over winter. By contributing to the survival of non-migrating butterflies, Asclepias curassavica could be promoting OE persistence, but the US occurrence of this milkweed is unclear. We hypothesized that the abundance of Asclepias curassavica in US metro areas in California, Florida, and Texas have increased in recent years because of the popularity of monarch conservation and public campaigns that have encouraged the planting of this species. We collected publicly available iNaturalist data on milkweed plants (genus Asclepias) to assess the proportions of tropical to native species and compared the proportions of tropical milkweed observations across years, states, and metro areas. The results showed that states differ significantly (p<0.001) in the proportion of milkweed plants that are tropical (Florida > California > Texas), and metropolitan areas within each state largely do, as well. The proportion of tropical milkweed within each metropolitan area has changed little over time, suggesting less uptake than predicted.