Stored data is a critical component of any application. The stored data component of mobile applications (apps) presents special considerations. This paper examines stored data for mobile apps. It identifies three types of mobile apps and describes the stored data characteristics of each type. It proposes decision factors for selecting a data storage approach for a mobile app and the impact of the factors on the usability of the app. The paper surveys over 70 apps in a specific domain (that of walking the Camino de Santiago in Spain) to examine their data storage characteristics. It also presents a case study of the development of one app in this domain (eCamino) and how the decision factors were applied in selecting the stored data approach for this app. The paper also discusses the implications of the research for apps in other domains. The paper concludes that in general the data storage approach selected for a mobile app depends on the characteristics of the situation in which the app will be used, but in the domain examined one particular approach (synchronized data storage) has clear benefits over other approaches.