Badges, the Items it is all About by the total distance they have traveled (via in game actions, Badge®s does not track user positions).
Note, the units are not entirely standard, but clickable for their definition!
Link: Longest Traveled Badge
Note: Technically these numbers should be ever-increasing, due to database cleanups of wrong structures they might occasionally decrease.
Stay up to date with (most) of Badge®s statistics via the Significant Statistics Changes page.