Enterprise Architecture (EA) is an important tool when developing e-governments and smart cities as it can help improve the alignment between business goals and Information and Communication Technologies (ICT) implementations. Although some studies have been performed to study the applications of EA in public sectors, governments, and cities, most of such studies are scattered and there is no strong research stream. As a result, it is difficult to effectively accumulate relevant knowledge and experiences. In this research, we attempt to explore research streams and trends by analyzing why existing studies were conducted, what outcomes were produced, and what methods were used in these studies. Starting from these three questions, a thematic framework was developed, and a literature synthesis was presented. The result shows the complexity of this area, the importance of balancing technical factors and non-technical factors, the challenges brought by non-functional requirements. Despite the importance of EA frameworks, few studies have been found in which government or city relevant requirements were addressed in a general way. Such findings are expected to provide useful insights for possible future research in this area.