Jobs in Unites States of America:
A job is a regular activity performed in exchange for payment, usually as one's occupation. A person usually begins a job by becoming an employee, volunteering, or starting a business. The duration of a job may range from an hour (in the case of odd jobs) to a lifetime (in the case of some judges). If a person is trained for a certain type of job, they may have a profession. The series of jobs a person holds in their life is their career.
      Unemployment occurs when a person is available to work and seeking work but currently without work. The prevalence of unemployment is usually measured using the unemployment rate, which is defined as the percentage of those in the labor force who are unemployed. The unemployment rate is also used in economic studies and economic indices.
   There are many sites in USA and also worldwide that advertise about USA Jobs. The Federal Government's Official Jobs Site is: http://www.usajobs.gov/
Some Other Famous Sites for Jobs in USA are:

http://www.usajobs.com/
http://www.topusajobs.com/
http://www.bestjobsus.com/
http://www.americanjobs.com/
Reference: http://www.google.com.pk/