The war years of the early 1940s saw a sharp increase in demand for concrete blocks
. In 1947 K.S. built a new plant approximately one mile east of Stahl’s Quarry, where the corporate/sales offices and Middleburg production facility still stand. In 1956, after 34 years in business, K.S. sold the company to his son, Paul. That year, for the first time ever, more than one million blocks were produced in a year and the company grew to 15 employees. A Besser V3R Vibrapac block machine was installed in 1961 and total production was 1,875,930 units for the year. The company grew rapidly and by 1966 annual production had increased to 3,169,362 units and distribution included all of Pennsylvania and the southern tier of New York. In 1967 Beavertown Block Co., Inc. merged with Markle Concrete Products Company in Pleasant Gap. In addition to a new automated mixing system at the Middleburg facility, this merger enabled the company to provide better service and products. By 1969 production exceeded 4.3 million units.
The 70s saw continued growth for the company
. In 1971 a new corporate office building was completed in Middleburg, with 75% of the materials used in the construction designed and manufactured by Beavertown Block Co., Inc. and Beavertown Cast Stone, Inc. (a separate business founded by Paul Kline in 1966 specializing in the manufacture of custom precast concrete structural and architectural panels). The Middleburg plant became completely automated in 1972 with the installation of a BECO ABC block-handling system and a PACO automatic block cuber. Having grown to 63 employees, the company continued to expand with the purchase of the Delvan Block Company, a competitor located in South Williamsport.