That would be American Libraries, the magazine. According to a new report, they are making progress in engaging through social media:
American Libraries and Social Media
Social media engagement continues to grow at a healthy pace. Since October 1, AL Twitter followers increased by 1,804 to 24,371 and AL Facebook fans increased by 252 page Likes to 5,364 with an average post reach of 2419 people (an increase of 1360). [Facebook no longer counts “Impressions,” as post reach is more reflective of how many people the content reaches.]
The AL Pinterest page added one new board so AL now has 19 boards, not counting the 5 shared boards on the AL page. There are now 5017 followers on Pinterest, an increase of 596.
Source: Fiels, Keith Michael. Report to [ALA] Council and Executive Board, December 12, 2013.