## 1 Introduction  
The emergence of the COVID-19 pandemic has prompted a new view on the relationship between sustainable development and worldwide tourism. Over the past decades, this relationship was mainly investigated from the perspective of the unwanted effects of tourism--often in the form of mass tourism--on the environmental quality of regions or cities (see, e.g., [1, 2]). Spatial density and geographical proximity were the characteristic features of mass tourism. However, recently, we have observed a significant shift in the spatial behavior of visitors to regions and cities; the contagious effect of the coronavirus has caused a global awareness of the health risks of high human density in entertainment centers, theatres, museums, and other public events. Consequently, new sustainability motives in the tourism sector found their origin in environmental concerns and health concerns (in agreement with Goal Three of the SDGs). Density and proximity were increasingly seen as negative sustainability externalities, with the consequence that tourists and recreationers were re-discovering spacious and green areas ranging from urban parks to regional or national parks. Such green areas were not completely serving as substitutes for densely populated tourism centers, but to some extent, they acted as complimentary amenities mitigating COVID-19 infections. This has profoundly impacted the steady pattern of tourism trends over the past years. The global rise in welfare, the ongoing rise in leisure time, and the improvement of geographical accessibility have, over the past decades, prompted an unprecedented increase in tourist movements, not only locally or regionally but also internationally [3, 4]. Agglomerations with favorable connectivity have especially benefitted from this megatrend. This holds for tourist hubs such as Paris, Rome, Amsterdam, San Francisco, New York,Bangkok, or Tokyo favoring urban tourism and for Malaga, Nice, Antalya, Bali, Cape Town, or Miami favoring beach and nature tourism prominently. Clearly, this demarcation of tourism types is less sharp, and mixed cases are abundantly available. Even the traditional dichotomy between urban and rural tourism never led to entirely disjointed appearances of these two types of tourism, as both centripetal and centrifugal forces (for instance, urban tourists who also make trips to rural areas or rural tourists who also make trips to cities) co-exist and interact. It is thus clear that both urban agglomerations and rural areas exert both repulsion and attraction forces on visitors. From the perspective of sustainable tourism behavior, the trend towards less concentrated mass tourism patterns and more spatial dispersion is already present over a longer period. Consequently, environmental attractiveness factors and human health considerations come together in the period of the COVID-19 pandemic. It seems plausible that sustainability motives--interpreted in a broad sense--will exert a far-reaching impact on tourism behavior in the future. Apart from wellness tourism [5; 6; 7], health considerations have only played a modest role in quantitative tourism studies in contrast to sustainability considerations in modern tourism research. However, the COVID-19 pandemic has generated a different mindset in the motivation and decisions of tourists, in particular regarding modal choice, destination choice, and daily--often crowded--tourist amenities choice (e.g., shopping malls, museums, theatres). Currently, the pandemic is viewed as a risk of density for people and a health threat due to geographical proximity. Therefore, the question arises whether COVID-19 will act as a 'game changer' for contemporary (mass) tourism. The present study aims to assess the tourism implications for Las Vegas as a center of mass tourism (mainly gambling and entertainment activities) and addresses the question of whether health concerns may be responsible for significant changes in the geography of tourism in this area.