Google Maps Directions

Directions in Google Maps are provided over contiguous areas of the Earth's surface.

Contiguity in Google Maps directions

The term contiguous sounds a bit technical, but the concept is quite simple. It is useful to understand what it means if you are planning any complicated trips.

• In the strict definition, contiguous means very closely connected in space or time, or connected without a break, or contained within a common boundary. 

You can drive without without a break from Florida to Alaska, as it's all one land mass. But, in most contexts, one wouldn't say these states are very close together. Also, you need to cross Canada;  that is, you need to leave the common boundary of the USA. So the trip from Florida to Alaska is contiguous in one sense of the strict definition, but not in two others. 

In the context of driving directions "contiguous" is usually taken to mean connected without a break. But don't let the 'Florida to Alaska' example lead you to think that contiguous driving directions require a contiguous land mass. For instance, Google Maps directions can be found from England to other European countries, and all these journeys require crossing a stretch of water. 

So the break in continuous without a break is rather arbitrarily defined by Google, perhaps based on  political or other issues. For instance, these days, England and France are not in contention, so directions are given between London and Paris. But you can't get directions from Cairo in Egypt to Jerusalem in Israel. But even if countries get on well, you aren't guaranteed directions in certain situations. For instance, I haven't found any directions from European to African or American cities. 

So Google maps has an inconsistent limitation. Going from London to Dublin is just the same as going from London to New York, in the sense that both involve a hop over some water. You might, for instance, imagine an art loving jet setter wanting directions on how to get from Tate Modern to MoMA, why can't Google provide them, including directions to Heathrow and from JKF?

Examples of where contiguity breaks down for Google maps directions:

• Between continents, e.g. between Africa and America, or Australia and the USA.
• Between North and Central America. You can get directions from Houston to Anchorage, or Toronto,  but not from Houston to Mexico City.
• Between Central and South America.
• Between Europe and Russia. You can't get Google map directions from London to Moscow. Note that Multimap, a UK based company, does provide such directions. But Multimap also has flaws, it doesn't cover as many countries as Google Maps. 

Strangely, Google Maps is prepared to give directions from England to France, without specifying towns, but not from USA to Canada. It may be that Google reckons there are just too many routes between USA and Canada to make it sensible to offer suggestions, but surely it should offer a few just to show that you can actually get from the USA to Canada!

• When testing for contiguity between two countries try and include detailed from and to information, or at the names of major towns.

Various sites present long lists of discontiguities, but it's more fun, and more up-to-date and accurate, to see if Google directions can get you from A to B by playing with the from and to boxes.

Google Maps Directions: References & Further Reading 

Google Maps: General References

en.wikipedia.org/wiki/Google_Maps#Directions