The U.S.political ecology experienced significant changes since the two years ago Obama took the office of presidency. Politically，the balance of power within and between the Democratic and Republican parties has clearly transformed，and political polarization has occurred，while the overall political trends have swayed backwards to the right. Economically，inequality of wealth and income has further enhanced，governmental regulations over market have been tightened，and fiscal conditions of governments at every level have deteriorated. Socially，imbalances of population growth among races and ethnics，and regions have continued，public cognition of domestic and international issues have somehow changed，and developed technologies and their applications in social communication and networking have provided driving forces to self-insulation and polarization of public political positions. These changes have and will continue to have significant impacts on American domestic and foreign policies.