Due to the need for firefighting apparatus to be highly visible, they are, similar to other emergency vehicles, painted in conspicuous colors, such as white, yellow, orange, or red most frequently and famously, fire engine red. While red remains the most common color for firefighting apparatus, it is not required and depends highly on individual needs, traditions, and safety research.[7] For example, the Chicago Fire Department has a long-standing tradition of painting their apparatus black over red, a practice that has caught on far beyond Illinois.[7] Neighboring departments will also often use different colors to distinguish their apparatus.