L.A. see hundreds of cart-pushing entrepreneurs.
Program was cheaper than private schools.
The airport says program saves $200,000 a year
President Obama's L.A. visit will bring an onslaught of traffic.
Protesters say the program too often results in wrongful deportation.
Activists call on China to stop abusing North Korean refugees.
After the deadline, the unions and stores pull it together.
Mayor Antonio Villaraigosa and Eric Garcetti attend.
Program helps USC connect with community.
L.A.'s black leaders discuss job-creation policy, inequality.