in conjunction with the conferences. From their inception, the conferences and training courses have been characterized by exchanges of ideas among practitioners, program managers and policy makers. APT has also presented training courses, workshops and symposia as stand-alone events, independent of annual conferences. Publications APT disseminates information through its website, electronic and print publications, and digital archives. The organization’s flagship publication is the APT Bulletin, a peer-reviewed journal published quarterly. The newsletter, the Communiqué, is published bimonthly and circulated through email. APT periodically publishes books in the field of heritage conservation. The most recent publications are the Preservation Technology Primer, a collection of articles from the APT Bulletin, and the second edition of Introduction to Early American Masonry, by Harley J. McKee. To disseminate information on historic building materials and systems, APT created the Building Technology Heritage Library (BTHL), a digital collection of historic building trade catalogs hosted by the Internet Archive. The collection is growing and had over 9,800 items in September 2018. Chapters As of November 2019 there are 21 local APT chapters, which allow interaction among members throughout the year. Fourteen chapters are in the United States, three are in Canada, with one in Australasia, one in Latin America, and new chapters for Europe and East Asia. Chapters host local events including visits to sites of interest to members, workshops, and symposia. Technical Committees Development and dissemination of technical information is mainly carried out by technical committees with specific focus areas. The technical committees are: Preservation Engineering, Sustainable Preservation, Modern Heritage, Documentation, Materials, and Codes. References External links Architectural conservation Historic preservation organizations in Canada Historic preservation organizations in the United States Non-profit organizations based in Illinois Organizations established in 1968