A survey of oligohaline and mesohaline tidal marshes along the upper reaches of eight tidal rivers in the Great Bay Estuary of New Hampshire was conducted to document the occurrence of eastern grasswort, Lilaeopsis chinensis, a state-listed, rare species. Historical sites were visited to assess the presence, absence, or significant population changes of this rare coastal species. We re-located four of five historically documented element occurrences, noted the plant's potential expansion on several rivers and a decline at three other sites, and identified a new occurrence on a river system with no prior documented accounts. The results suggest that overall, L. chinensis has been relatively stable for the last 60 years, although the loss of plants at three of the sites suggests it is threatened by continued development (dams and tidal restrictions) and associated impacts to water quality.