||Walking is regarded as the best moderate to vigorous physical activity (PA), which benefits peopleâ€™s mental and physical health by decreasing obesity, increasing disease control, and relieving depression. Hence, promoting walkability is critical to sustainable development. In this thesis, we analyze the determinants of walkability regarding sociodemographic status, street design, land-use, accessibility to public facilities, and neighborhood safety in Salt Lake County, Utah, United States. A four-component walkability index is employed as a quantitative measurement of street design and land-use the validity of which is tested at various geographic scales. The multiscale test results indicate that current neighborhood design in Salt Lake County only supports peopleâ€™s 20 minute walk. By building multivariable models and spatial regression models, we find that people with high education levels tend to walk more and neighborhoods with compact design are more walkable than others. Neighborhood amenities are further investigated using latent variable modeling and the model result suggests that accessibility to public transportation can help promote walking. Although street connectivity is still a good indicator of walkability, it is less influenced by urban development compared with other walkability indices.