This paper looks at intellectual connections in tourism studies through a co-citation analysis of its source knowledge. Reference sources from articles in Annals of Tourism Research are analyzed to describe source subject clustering and evolution over the last two decades. The subject clustering, connections and evolutions of twelve major source knowledge domains (namely, authenticity, tourist experiences, tourism planning, resident attitudes, tourism impacts, tourism area lifecycle, consumer behavior, backpacker tourism, performance approach, paradigms in tourism, dark tourism, and mobility) are visualized, described and discussed by four lustra (1998–2002, 2003–2007, 2008–2012, and 2013–2017). Implications of these source knowledge connections and evolutions for tourism studies are then reflected, and limitations of this research are also acknowledged. •Co-citation analyses of source knowledge for tourism studies•Describe and discuss intellectual connections and source knowledge network evolutions•Offer reflections on tourism studies from an evolutionary perspective