Communication in online communities that unite residents of certain localities contributes to the formation of territorial communities and the image of a place of residence as “one’s own”. In this study, the objects of analysis were VKontakte groups initiated and moderated by ordinary residents of settlements included in Yekaterinburg and Chelyabinsk agglomerations with a megalopolis core. The sample included 14 such online communities. The subject of the analysis is the topics discussed in online communities, which, based on a preliminary analysis of real practices in these agglomerations, were defined as constituent elements of the implementation of territorial identity policy by government bodies and other political and non-political actors to whom the institutions of public administration have delegated the relevant functions, powers, resources and responsibilities. The time period of the study is from the beginning of January 2023 to the end of March 2024. Big Data analysis technology was used. With its help, all posts, their tone, number of views, likes/dislikes, comments and reposts were analyzed for 12 main types of events that contribute to the formation of territorial identity at the city and local levels, when both the locality and other people living in it become “ours” to an equal extent. The analysis showed a high degree of similarity in the nature of communication on these issues in the VK groups of residents of the Yekaterinburg and Chelyabinsk agglomerations. The most significant issues were related to toponymy, holidays and memorable days, and educational courses.