To identify the left and right hinges, look for the direction of the hinge pin. The side with the hinge pin that is closer to the center of the door or object is typically the left hinge. Conversely, the side with the hinge pin that is further from the center is the right hinge. This method is based on the standard practice in the United States, where doors are typically hinged on the left side for easier passage through doorways.

This method is grounded in the historical and practical considerations of door design. In the United States, doors are commonly hinged on the left side to accommodate the majority of right-handed individuals, who are more likely to open doors from the outside. According to a study by the National Institute of Standards and Technology (NIST), approximately 90% of the population in the United States is right-handed. This preference has influenced the standardization of door hinge placement, making it easier for the majority to open doors without the need to reach around or step over them. Additionally, the left hinge placement allows for a more streamlined design of doorways, as it minimizes the space required for door swing. This practical approach has been widely adopted in residential, commercial, and institutional buildings across the country.