The presidential race between Hillary Clinton and Donald Trump in 2016 played out not only across newspaper pages and television screens, but on Facebook walls, YouTube channels, and in Twitter feeds. Stories, memes, and videos from the unusual race were amplified through vast user networks, demonstrating that social media have become deeply embedded in politics and participa-tory practices. Yet the same affordances of online networks that facilitate citizen participation also open up participatory opportunities to another group that is not traditionally considered within the bounds of the national public sphere: non-citizens. This quantitative study takes up the question of how these affordances are being used for transnational political participation by examining the use of Twitter by Scandinavians in the 2016 American election. Drawing on a massive keyword-based collection of tweets made during the run-up to the election, user metadata is analyzed to find users in Sweden, Norway, and Denmark. Over a quarter of a million tweets sent by these users are analyzed, looking at communicative patterns, use of language, media sharing, hashtag use, and attempts to interact with Americans - as well as the degree to which Americans interacted with Scandinavians. A combination of comparative analysis, content analysis, and network analysis is employed. The findings suggest that, while limited in overall numbers, Scandinavians actively participated in the American sphere through Twitter, often in ways very similar to Americans. Although most of these foreign users gained little traction within the American public sphere, the findings also show that those who did have transnational exchanges with Americans were disproportionately Trump-leaning, pointing to the use of Twitter for the formation of cosmopolitan nationalist networks.