Book excerpt: Questions of migration and citizenship are at the heart of global political debate with Brexit and the election of Donald Trump having ripple effects around the world. Providing new insights into the politics of migration and citizenship in the UK and the US, this book challenges the increasingly prevalent view of migration and migrants as threats and of formal citizenship as a necessary marker of belonging. Instead the authors offer an analysis of migration and citizenship in practice, as a counterpoint to simplistic discourses. The book uses cutting-edge academic work on migration and citizenship to address three themes central to current debates – borders and walls, mobility and travel, and belonging. Through this analysis a clearer picture of the roots of these politics emerges as well as of the consequences for mobility, political participation and belonging in the 21st century.