Inter-city collaboration: Why and how cities work, learn and advocate together

City governments are at the forefront of public problem-solving. As they deliver services to residents and work to tackle complex social challenges, they often coordinate and communicate with each other. Against the backdrop of globalisation and urbanisation, which have been documented and analysed widely, the phenomenon of inter-city collaboration (ICC) has remained understudied. In this article, we examine existing and emergent patterns of how and why cities collaborate. We conducted a desk review of ICCs in 64 US cities. We interviewed city leaders in US and international cities (N = 13) and leaders of ICCs (N = 20). We also surveyed leaders from 47 US cities. Through our analysis, we put forth an analytical framework of ICCs, describing the forms they take and the value they deliver. We identify various forms of value ICCs produce for cities and examine under what conditions they are likely to be effective. While not all collaborations are successful, ICCs have the potential to generate substantial benefits through mutual learning, economies of scale and the power of collective action. Intentional design and management of ICCs can make them effective platforms of ‘horizontal governance’ and solving collective action problems.