text: These different ways of limiting car usage have also spread to the United States. President Obama has large goals to "curn the United States' greenhouse gas emmisions". Recent studies have shown that Americans are buying fewer cars and getting fewer licenses as the years go by. There has also been a reduced amount of car ownership per household. Many sociologists believe it will have "beneficial implications for carbon emissions and the environment" with transportation being the second largest source of the United States emissions. In a span of nine years, a study found that driving by young people had decreased 23 perecent. Discussions at the Mobile World Congress lead to a plan for a world where personal vehicle ownership it impractical or undesirable.