The Pittsburgh region, while well known for steelmaking, was likewise an important glass manufacturing center in this country's history. This book provides detailed accounts of the region's glassmakers from the first factory dating to 1795 through 1910. Glassmaking started out modestly with small glasshouses in Pittsburgh and up the Monongahela River in New Geneva during the final few years of the 18th century. By the close of the 19th century, the Pittsburgh region was producing more than half of all domestic window glass and the lion's share of most other forms of glass in the United States. The original purpose of this manuscript was to assemble and record as accurately as possible the history of all of the glassworks and the glass manufacturers that operated them in Pittsburgh and the immediate surrounding region. This book was designed to be a reference guide for anyone who is interested in the history of glass in western Pennsylvania. The years companies were operating, where the glassworks were located, what types of glass and specific glass items did they make, and what marks did they use is just some of the information that can be found in this book. There are hundreds of individual companies and name changes listed in this volume. It contains as much information about each company that could practically be included. Even the most minor name or address change was recorded exactly as noted by contemporary sources. As much as possible, contemporary reference sources, such as city directories, early newspapers, maps, and journals were used to provide accurate and complete histories of the glasshouses. Generally, the better-known companies will have much more of their history available. However, every known glassmaker and glasshouse was included, regardless of how little information about them could be found. This book is intended to aid researchers in the determination of the age and the origin of marked pieces as well as narrowing down potential manufacturers of unmarked objects. The liberal reproduction of original advertisements and maps as well as the photographs of glass marks were included to complement and augment the narrative. The format of this book was established to facilitate its use as a reference guide.