  Determining the geographic focus of digital media is an essential first step
for modern geographic information retrieval. However, publicly-visible location
annotations are remarkably sparse in online data. In this work, we demonstrate
a method which infers the geographic focus of an online document by examining
the locations of Twitter users who share links to the document.
  We apply our geotagging technique to multiple datasets built from different
content: manually-annotated news articles, GDELT, YouTube, Flickr, Twitter, and
Tumblr.
