There are a number of ways to go about becoming a police officer. One of the most common ways is to attend a police academy, a school where officers are trained. In the United States there are academies in every state. They also exist at the federal level (see the section on Special Agent). To join the academy, you must have a certain level of physical and mental aptitude. These requirements are published, so that potential applicants don't waste time applying for spots they won't be accepted into.
Many academies require that their recruits be sponsored by a police department. This is to make sure that sensitive information, such as interrogation techniques, crime scene processing, and tactical decisions are not made public. In order to be eligible to learn police methods, one must prove himself capable and trustworthy.
Some state academies include:
Alabama Police Schools
Alaska Police Schools
Arkansas Police Schools
Arizona Police Schools
California Police Schools
Florida Police Schools
Ohio Police Schools
Texas Police Schools