We examine the content of the official Facebook pages of 502 Italian municipalities over the period 2016–2018 to empirically infer the motivations of municipalities to use Facebook. Our inference is mostly based on the relationship between the main topics discussed by the municipalities on Facebook and the most related municipal expenses per capita, which are reported by function in municipal financial statements.

Using a structural topic modelling analysis consisting of an unsupervised machine learning procedure, we find that Italian municipalities mostly post on five semantically different topics on their Facebook pages. More importantly, each topic's prevalence is positively associated with the most related municipal expenses per capita by function. Furthermore, additional covariates significantly influence each topic's prevalence. Within the framework of legitimacy theory, these results indicate the strategic usage of Facebook by Italian municipalities for self-promotion and political marketing aimed at enhancing their political legitimacy and consensus among citizens.

Our findings contribute to the literature on voluntary e-disclosures of local governments and on interactions between local governments and their citizens through social media. Therefore, these findings may have practical implications for public regulators, managers, and other users of social media.

我们检查了 2016-2018 年期间 502 个意大利城市的官方 Facebook 页面的内容，以经验推断城市使用 Facebook 的动机。我们的推断主要是基于市政当局在 Facebook 上讨论的主要话题与最相关的人均市政费用之间的关系，这些人均市政费用在市政财务报表中按职能报告。

使用由无监督机器学习程序组成的结构主题建模分析，我们发现意大利市政当局大多在其 Facebook 页面上发布五个语义不同的主题。更重要的是，每个主题的流行度与按功能划分的最相关的人均市政费用呈正相关。此外，额外的协变量显着影响每个主题的流行度。在合法性理论的框架内，这些结果表明意大利市政当局战略性地使用 Facebook 进行自我宣传和政治营销，旨在增强其政治合法性和公民之间的共识。

我们的研究结果有助于有关地方政府自愿电子披露以及地方政府与其公民通过社交媒体互动的文献。因此，这些发现可能对公共监管机构、管理者和其他社交媒体用户具有实际意义。