While I've been researching driving from Miami to Key West, I've noticed that a lot of the the establishments along the way list their locations by "Mile Marker." In other words, they use their mileage from the very end of Highway 1 (in Key West) to designate where they are.
The closer you get to the end of the road in Key West, the smaller the numbers get. Until, of course, you end up with Mile Marker 0 in Key West, itself.
(Photo from KeyWestWeb.net, since I haven't been there.)
There's something to be said for Mile Markers.
When I first moved to Minnesota, the first time I drove home to South Dakota to see my parents, I was driving west along I-90 and found myself getting really excited as I got closer and closer to Mile Marker 1 - the last stretch of I-90 in Minnesota before crossing in to my home state. Sure, I still had about 2 hours of driving ahead of me, but just knowing I was almost to my home state made me feel like I was almost home.
Of course, the countdown only works in one direction per highway. Going the other way, you only know that the numbers are going up. Unless you've travelled the road a lot before, or checked a map, or can just guess *really* well, you don't know what the top number is going to be.
Milestone birthdays are kind of that way, too. As you look down the road you can see the markers coming.
And although you always know how far you've come from Zero, you usually don't know how far you have to go until you get to your next destination.