Tidal wetland habitats – saltmarsh and mangroves – are highly valuable and provide numerous ecosystem functions and services, yet they are susceptible to human disturbances and climate change. Worldwide, there is increasing evidence that such disturbances are driving shifts in tidal wetland community composition and distribution, with mangroves commonly displacing saltmarshes. Tidal wetlands have been mapped on multiple occasions by NSW DPI across 117 estuaries since 1980 and we use these data to provide one of the most comprehensive assessments on how the extent of these habitats has changed over time. We report a general trend of mangrove expansion and encroachment into saltmarsh habitats, with considerable proportions of saltmarsh and mixed (i.e. interspersed saltmarsh/mangroves) habitats shifting to mangrove dominated areas. However, these patterns were dependent on estuarine geomorphology. Changes in mangrove and saltmarsh extent in relation to climatic and anthropogenic disturbance variables will also be discussed. Our results on mangrove/saltmarsh expansion and contraction will contribute to the management and conservation of tidal wetlands in NSW.