- Updated statistics: https://lawcenter.giffords.org/facts/gun-violence-statistics/
- Days since the last mass shooting: https://publichealth.jhu.edu/center-for-gun-violence-solutions/data/annual-gun-violence-data
- Automatically updated sign: http://www.gunviolencearchive.org/
- Days since each mass shooting: https://www.nytimes.com/interactive/2017/11/05/opinion/editorials/editorial-debate-gun-control.html
- Other counters: https://www.theguardian.com/us-news/ng-interactive/2017/oct/02/america-mass-shootings-gun-violence
- Weekly school shootings: http://www.latimes.com/projects/la-na-school-shootings-since-newtown/
- CDC 2018 Gun Deaths Report: https://wonder.cdc.gov/controller/saved/D76/D48F344