Through a combination of mobile website visits, content analysis and librarian interviews, the authors surveyed 143 U.S. libraries. The results show that over 97% of the libraries have at least one mobile website or APP, and the RWD mobile website device has become the most mainstream mobile service platform. Diverse social media sectors are widely adopted in the libraries to promote the services to mobile users. Libraries are actively developing new service features for remote access, such as APP download links, mobile reference services, QR/bar code scanning, location navigation, mobile printing and so on. The U.S. libraries are terribly striving to meet each local community's remote access needs via new technologies. Compared with the mobile services provided by urban libraries in the U.S., the public libraries in China need to strengthen the popularization of mobile services, the construction of mobile websites and APP, the application of social media, and the expansion of mobile service functions.