This study uses theories on dialogic accounting to assess whether online interaction through social media is used as a mechanism of public information and stakeholder engagement by Canadian and American public transportation agencies. We embraced a quantitative methodology in which content analysis was performed on the Facebook and Twitter accounts of 35 transit operators in Canada and the United States. We categorized the contents of 1,222 Facebook posts and 2,615 tweets, assessed which level and what type of interaction was effectively reached for every category, tracked whether and how agencies reply to comments on their posts, and assessed the general tenor of the discussion. Our results show that public transportation agencies often take advantage of their presence on social media to provide the public with information on their services and to perform activities associated with stakeholder engagement. However, we have found some significant differences in the utilization of social media by public transportation agencies, all of which are discussed in the "Conclusion" section of this article. Twitter is most often used for public information messages, while Facebook appears to be used more to publish content in a dialogic perspective that creates two-way, collaborative conversations with users. In terms of practical implications, our study suggests that a broader and more continuous commitment to interaction between users and stakeholders on social media would create new opportunities for improving transparency and, indirectly, the services of public agencies.