Twitter might be a big echo chamber of noise at the best of times, but there is an enormous amount of data flowing through it.
The so-called firehose of activity gives those trying to do interesting things with it an opportunity to see destinations in a different light.
The folk at Mapbox have been trying to decipher not what people are saying about a city, but where they come from.
This first iteration shows the entire world and the volume of tweets based on whether they were posted by a local or a tourist.
Red is tourist, blue is local - established by the home location of the user.
When a user moves out of their home city and posts in a new destination their tweets turn from blue to red.
You get the idea.
The above shot is London (note Heathrow Airport in the west), below in San Francisco, with its cluster or tourist tweets around Fisherman's Wharf and on Alcatraz Island.
Or New York, where there is a lot of tourist activity in mid-town (but little from either camp in Central Park):
Where this could become useful for travel brands further down the line, especially tourism boards, is diving deeper into the origin of the tourist.
For example, a destination would be able to say with a fair degree of accuracy that, based on Twitter use and crunching with visitor data and ratios, tourists from the UK tend to hang out in Times Square more than their French counterparts.