This data release contains three datasets for the Pitcher's thistle (Cirsium pitcheri) reintroduction experiment, started in 1994, at the Portage Lakefront unit (formerly called Ogden Dunes), Indiana Dunes National Park, Porter County, Indiana. This plant species is a Federally threatened monocarpic perennial plant endemic to the sand dunes of the western Great Lakes. There are three csv files included in this data release. One file contains count data for plants from 1994 to 2000 from early-, mid-, and late-successional habitats. The other two files, with identical structure, contain demography data for two populations (Mid- and late-successional habitats) from 2001 through 2023. These data sets provide the spatial distribution of plants in the population and the life stages encountered from 2001, when we began tracking individual tagged plants, through 2023.