Mitigating climate change and improving urban livability is prompting cities to improve sustainability of urban transportation and logistics. Cargo bikes, in combination with urban transshipment points, are gaining momentum as a green last mile alternative. Although a wide body of research proves their viability in dense urban areas, knowledge about planning urban transshipment points is very limited. This also entails the siting of such facilities and the assessment of effects on emissions. This study therefore presents a first quantitative scenario-based model that assesses the impacts on a district. It examines different strategies for siting urban transshipment points in a single district and its effect on traffic, the carbon footprint, and air quality to give strategic insights where to create candidate locations for such facilities. Our result contributes to knowledge of planning urban transshipment facilities and assessing the impact of different configurations. The findings demonstrated that the use of cargo bikes to make courier, express, and parcel (CEP) deliveries in urban districts could reduce greenhouse gas (GHG), particulate matter (PM10), and nitrogen oxides (NOx) emissions significantly. However, the choice of vehicles completing inbound and outbound processes and the strategies for siting urban transshipment points display widely differing and even conflicting potential to reduce emissions.