Very little is known about how smoking and other tobacco use is regulated in outdoor and semi-enclosed spaces across transit systems. The purpose of this study was to understand how American transit systems are regulating cigarettes and other tobacco products, including smokeless tobacco and e-cigarettes, in outdoor or quasi-outdoor spaces. Within four regions of the United States, a purposive convenience sample was taken of the top five volume American transit systems (n = 20) based on annual ridership. Each transit authority website was systematically reviewed to produce a cross-sectional study of the published policies regarding tobacco product use for indoor, outdoor, and quasi-outdoor spaces of transit property; rules regarding cigarettes, smokeless tobacco and electronic cigarettes were identified. Policies regulating tobacco use were enacted by transit systems and/or the cities and states in which transit systems are located. The majority (80%) of transit systems banned smoking in outdoor areas; few prohibited smokeless tobacco use (15%, n = 3) and some disallowed e-cigarettes (30%, n = 6). Violation consequences ranged widely from none to verbal warnings, ejection from transit property, fines, and imprisonment. Regulating smoking in outdoor or quasi-outdoor environments is common in American transit environments. These policies can help protect vulnerable populations from exposure to secondhand smoke and communicate a tobacco-free norm.