Police departments send personnel where they think they'll be needed and have officers "patrol," or cruise various areas where there have been (or they expect there might be) problems. If there is no police officer in your area, it is easy to contact the police using an emergency or non-emergency telephone number, by email or, in some cases, using a smartphone app.
Call 911. This is the universal emergency number. At home (with only a few exceptions), it will get you your local police department and emergency services. On the road, it will get you to the sheriff of the county where your cell phone's calling from. A dispatcher can respond or route your call to the proper department. Again, this is a number that should be used for emergencies only. In some areas, 911 services are stretched too thinly, and non-emergency use of the system (directions, hunting license information, name of a good restaurant – yes, people do call 911 and ask these questions) can tie up lines or dispatchers and deny service to real emergencies.
Use the Internet
Use the Internet to search for your local police department's contact details. You should find a business or "non-emergency" number or email address as well as the number for emergencies. This non-emergency number should get you to someone at the department, usually a dispatcher, who can answer your question or put you in contact with a specific officer or administrator (like a watch commander or the chief). Some police departments have also developed smartphone apps that let you connect with your local law enforcement or public safety agency.
Pay Attention to Local Police Patrol
Look around. Do the police patrol around your location frequently? If you're on the road, how many and what kind of officers have you seen? City police patrol city streets, and county officers patrol rural areas and highways. Your state patrol is charged with highways and interstates. If you pay attention, you'll notice patterns, and can use this to help locate local police.
Find special-duty officers in the community. School liaison officers, transit police and community service officers are examples of officers who are assigned to duties in the community who serve in primarily educational or peace-keeping roles. They're present at many community activities, festivals and meetings. They generally appreciate your interest and are happy to assist in any way possible.
In Everyday Life
Pay attention in your everyday activities. Police officers, like most emergency personnel, have families and lives outside of work. Like the rest of us, they shop, go to their children's school concerts and sports contests. Unlike us, though, they are never off duty. (There could be a police officer whose child is a little league teammate of yours.) Their responsibility to respond is only a mandate in situations where a crime is being committed or public safety is at issue and is within their area of responsibility or jurisdiction. Otherwise, their duty may simply be to notify law enforcement of the problem or respond the way any responsible citizen would. Either way, they can help.
In small towns, most people know a police officer or live down the block from one. People who live in big cities tend to think of them as an authority figure who exists only in the job. The success of any police department depends on its officers' abilities to maintain the professional authority of the big-city perception while providing the approachability of the small-town model.