Pro-gun people were also likely to tweet links from Fox Nation (e.g. Democrats Have a Full-blown Akin on Their Hands) and other recognizably right-leaning sources, but also frequently shared a number of news articles that, while they might not take a recognizable position, simply weren't posted by anti-gun tweeters (e.g. Mistake in Gun Bill Could Defeat the Effort from the Seattle Times.)

The new NRA "Stand and Fight" ad was also much discussed this week, with many links directly to the video on YouTube and to several stories about the provocative piece (Fox Nation: "NRA Thunders Home Principles With Powerful, Emotional Ad.")

On the anti-gun violence side, the White House dominates the conversation. The most popular link was BarackObama.com's Sami's story with 1874 tweets, a video about a young man whose father was killed in a mass shooting. President Obama's plan to keep our kids safe and reduce gun violence was also popular, with 1355 tweets. There are several other popular BarackObama.com links, plus the White House live stream site which covered Biden's Tuesday town hall on Facebook and Thursday speech in Connecticut.

There are a handful of closely related sites around grassroots campaigns, such UniteBlue with We Demand a Vote and Blastroots' Moms Demand Action for Gun Sense in America petition. But in general, the anti-gun violence conversation was sparser, both in terms of number of sites and number of tweets. There simply weren't as many links being passed around on that side of the fence last week, at least not on Twitter.

Precious little was shared between the two communities. Both sides posted links to a Yahoo! news story about Colorado's new gun laws, and about a proposed Missouri bill that would make it a felony to propose gun control laws. Many pro-gun people also linked to BarackObama.com -- not any particular page, just the root site, with tweets such as "Shocker: http://BarackObama.com asks for gun violence stories, only shares ones that promote gun control." But that's about it. There were very few links recommended by everyone, which suggests that politically involved people really do live in two different information worlds.

In rare cases where the two sides do follow the same story, they often get it from different places, as when a Chicago woman was shot shortly after her sister attended Obama's Chicago speech on guns: people tweeted the story from the Huffington Post or from CNN, but not both.

There's a lot more here, including pieces on gun manufacturers refusing to sell in certain states, a DOJ memo saying that an assault weapons ban would not be likely to reduce gun violence, and a campaign to pressure Senator Marco Rubio to denounce the NRA.

And of course, there's always the The Onion.

About the data: This graph was generated from 330,245 tweets collected from Sunday evening to Sunday evening, captured by recording all tweets mentioning "gun violence," "gun control," "NRA," "gun rights," "gun owners," "gun laws," and several similar phrases. These tweets contained 38,515 unique links; this visualization is only the top 100. The most tweeted story has 2900 links, while the least tweeted has 171. Edges in this graph don't mean that two pages link to one another, but that a number of people (indicated by edge thickness) tweeted links to both pages over the course of the week. Made with Python for capture and processing, EC2 servers, Gephi for graph processing, and gexf.js for interactive visualization.

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