Patent ID: 7185021

Claim:
A navigation device for displaying dated map data, comprising: map storing means for storing the map data for a plurality of years; specifying means for specifying a specific year of the map data to be displayed and specifying specific data items from the map data that is to be emphasized when displayed; first display editing means for reading the map data of the specific year from said map storing means, and editing the map data to be displayed; second display editing means for reading map data of a different year from said map storing means, and editing the map data to be displayed; and displaying means for displaying the edited map data of the specific year and the edited map data of a different year; wherein the edited map data from the specific year and the edited map data from the different year are superposed on said displaying means at the same time; and wherein the superposed map data, includes at least one of said emphasized data items specified by said specifying means from a specific year, and normal data items from the different year.