National Geographic tracks social media traffic by categorizing referrers into 7 groups - search, social media, email, etc. Initial results showed search was the largest source at 42%. By honing in on social media, they saw visits from social media sites accounted for 8.4% of total traffic, more than doubling from the previous year. Tracking metrics like engagement showed social media visitors viewed an average of 4.2 pages per visit. National Geographic is able to analyze trends in traffic sources over time using this categorization method.