Around the same time, businessman David L. Clark began experimenting with his own candy creations in his home outside of Pittsburgh, Pennsylvania.

He began selling the Clark candy bar for five cents and shipping his creation to soldiers fighting in World War I.

[5] At the same time, Charles Miller started a business manufacturing and selling homemade candy in the Boston area.

In 1942, the U.S. Government requisitioned a "major portion of the production of the wafers, during World War II since the candy doesn't melt and is 'practically indestructible' during transit,"[4] This continued until 1945.

[9] After losing the license to Hershey, for a time Necco marketed an identical product called "Milk Chocolate Caramel Roll".

In 1978, after several reorganizations and seven company presidents, Domenic Antonellis was named its CEO,[6] a role he would play for nearly 30 years.

[1] Since April 2004, the Necco building at 250 Massachusetts Ave in Cambridge has been occupied by the Novartis Institutes for Biomedical Research.

[13] In 2005, the structure, which is still referred to as the Necco candy factory, was added to the U.S. National Register of Historic Places.

[1] In July 2013, United Service Organizations sued Necco in U.S. District Court for continuing to use their trademarks after their 2009 marketing deal had expired.

The 2011 news that the company was no longer for sale was accompanied by reports that the company had supplied the city of Revere with five years' worth of overdue reports required as part of a tax increment financing (TIF) deal the company had received from the city; those reports "seemed to indicate that Necco has—for several years—not created the jobs they promised in the TIF agreement"; as of March 2011 Necco employed 483 people, including 30 Revere residents.

[21] In March 2018, chief executive Michael McGee announced that, unless a buyer for the company could be found, most of Necco's workforce could be laid off as early as May 6, 2018.

[28] The assets of Necco were sold in a bankruptcy auction in May, 2018, with Spangler Candy Company having the winning bid of $18.83 million.

[29] However, Spangler backed out of the transaction and the company was instead sold for $17.33 million to Round Hill Investments, owned by billionaire C. Dean Metropoulos.

[3] They planned to restart manufacture of Necco wafers, Sweethearts and Canada Mints, but other Necco-owned brands would not be retained.