The anticipation of the publication of Go Set a Watchman has led to increased interest in Harper Lee’s other book, To Kill a Mockingbird. One of the strongest backlist titles ever published, sales of HarperCollins’s two trade paperback editions still jumped 226% in the period Feb. 2–July 5, 2015, compared to the similar period in 2014, at outlets that report to Nielsen BookScan. Meanwhile, sales of Grand Central Publishing’s mass market paperback rose 60%, selling 209,231 copies in the same period, while HC’s trade editions sold a total of 112,523 copies.

The mass market paperback of Mockingbird has been published continuously since it was first released in 1962. How Grand Central became the publisher of the mass market edition is a reflection of the consolidation that has taken place in the book industry since Mockingbird was first released in hardcover in 1960.

1960

J.B. Lippincott, one of the country’s largest independent publishers, publishes Mockingbird in hardcover.

1962

Lippincott licenses mass market paperback rights to Popular Library, which releases its edition two years after the hardcover.

1970

Fawcett Publications, looking to expand its book publishing arm as a complement to its magazine division, acquires Popular Library.

1977

CBS buys Fawcett Publications and adds it to its magazine and books division.

1982

CBS sells Fawcett to Ballantine Books and sells Popular Library to Warner Communications, where it becomes part of Warner Books.

1996

Warner Communications and Time Inc. merge and create the Time Warner Book Group.

2006

Lagardère, French parent company of Hachette Livre, buys the Time Warner Book Group and renames the publisher Hachette Book Group USA.

2007

Warner Books is renamed Grand Central Publishing, since Lagardère’s purchase did not include rights to the Warner name.

For its part, Lippincott was acquired by Harper & Row in 1978. H&R was eventually merged with the U.K. house William Collins in 1990 by Rupert Murdoch, who had acquired H&R in 1987 and Collins in 1990. HarperCollins will publish Lee’s Go Set a Watchman on July 14.