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.
No source gives an exact completion date. UPS's own first-quarter release of 27 April 2010 (the pin's reference) says the second phase of the Worldport expansion opened during the quarter, while PARCEL Industry (28 April 2010) and Wikipedia place the completed expansion in April 2010. Dated to the last day of April 2010 as an estimate; the previous 2010-04-27 was the press release date.
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.