In my carbon footprint, transportation was the biggest factor contributing to it. As I talked to many of my friends, I found that transportation was often the largest contributor in theirs also. Therefore, I think if a city used all “green” transportation it could become a much more sustainable city. In the city where I live, Houston, there is a bus service but also a Metrorail. From my observations, many people use the bus, but in downtown the metro or walking is how majority or people get from place to place. Here is a link about our Metrorail: http://www.ridemetro.org/services/rail.aspx Therefore, I think an ideal sustainable city would be built “up” rather than across New York City, where the average citizen walks around 4 miles per day, with a Metrorail system throughout . City developers could design the city for the main way of housing to be high- rise lofts or apartments, with most necessities in walking distance. For the places that are not in walking distance, I think a Metrorail is ideal. Through this idea, cars could be completely eliminated from a sustainable city. With the average car emitting almost 5 tons of carbon emissions per year, this could eliminate everyone’s carbon footprint substantially.