Although postal carriers are federal employees, the required exam to become a postal carrier is not the standard civil service examination required for other federal jobs such as law enforcement and judicial professionals. Instead, you must take a postal examination. The exams vary depending on the specific job you hope to get, so first you need to apply for an open position prior to taking your exam. The U.S. Postal Service will then send you an email asking you to schedule an examination.

Identify a Pennsylvania U.S. Postal Service job that interests you. Point your web browser to the USPS "Job Search" page, which is listed in the "Resources" section, and select "Pennsylvania" to locate jobs within your state. You can also specify a zip code, as well as any job functions in which you're interested. Click the "Start" button.

Apply for the job. Click the name of a job that interests you and read its description. Click the yellow "Apply" button at the top of the screen. Register for a USPS.com account if you haven't done so already. Provide your contact information, work and academic history and answer some questions about your work eligibility, veteran status and driving record. Click "Send Application" once you have completed all the steps.

Schedule your exam. Open the "Scheduling" email sent by the USPS. Click the link within the email to get to the scheduling page. According to its "Job Application System FAQ" page, the USPS has introduced the option of taking postal exams online, so you will either have the opportunity to take the exam somewhere nearby or on your home computer.

Report to the test location (or to the appropriate website) at the designated date and time. Get a full night's sleep and eat a good breakfast prior to taking the exam. The USPS will mail (and email) you a "Rating" after it has scored your examination and will invite you to continue the application process if your score is satisfactory.