The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
Happened as dated, per the source: "Disneyland opens | July 17, 1955."
History.com confirms "Disneyland...opens on July 17, 1955," matching the pin's stored date exactly, and notes the troubled opening day with counterfeit passes and overcrowding.
Wikipedia confirms Disneyland's dedication and press opening on "July 17, 1955," matching the pin's stored date, though it notes the general public opening followed the next day, July 18.
Something missing or wrong? Say it in your own words: a link that backs this pin up, a different start or end date and why, or a fact it lacks or gets wrong. The AI checks it against this pin's sources, searches for better ones, and adds any page that backs you up. The pin's own sources still count most.