Given the increasingly important role social networking services play as sources of information during disasters, this study aims to investigate how the municipal governments and their emergency agencies employed RSS or Atom, webcast, Facebook, Twitter, YouTube, and photo-sharing platforms in the major U.S. cities. Our findings show that the emergency agencies of San Diego, Los Angeles, and San Jose are the top 3 performers on the Web 2.0 services. Regarding the social networking services provided by municipal emergency agencies, New York, Los Angeles, and Philadelphia rank among the top 3 cities. While San Diego city government and its emergency agencies provide the most number of Web 2.0 channels, New York City and its emergency agencies have the highest number of services in Facebook, Twitter, YouTube, and photo-sharing platforms (Flickr, Pinterest, and Instagram). Because big cities can support better collaboration and communication during crisis if they provide more services on social networking services, under-performing cities can enhance their services by learning from the top-performing cities such as San Diego or New York City.