Navigation system

A navigation system, comprising:

• a receiving section that receives traffic information including congestion information;
• a congestion information acquisition section that obtains from the traffic information, items of congestion information related to a map information display;
• a congestion information extraction section that extracts, from the items of congestion information obtained by the congestion information acquisition section, a congestion information group with a specified congestion level;
• an overlap determination area creation section that, based on road links related to the items of congestion information within the congestion information group, creates an overlap determination area that extends both transversely and longitudinally for a specified distance from the road link;
• a grouping section that groups the items of congestion information having overlapping determination areas;
• an equal congestion level area creation section that creates an equal congestion level area by connecting the overlapping determination areas of the grouped items of congestion information;
• and
• a display control section that displays the equal congestion level area superimposed on the map information display.