Historic Info
From Illinois Digital Archives (info provided by the Libertyville-Mundelein Historical Society and Cook Memorial Public Library)--"Petranek's Pharmacy was located at 426 North Milwaukee Avenue near the southeast corner of East Cook Street and North Milwaukee Avenue. It was a successor to the historic Lovell's Pharmacy, owned by Kenneth Lovell, which opened for business at that site in 1876. Over the years, several people ran the pharmacy business. J. Swann took over in 1896; the pharmacy changed to Miller Drugs in 1946. Louis J. Petranek (Lou) took over in the late 1940s and the business became Petranek's in 1950. A fire in 1954 did $125,000 worth of damage to the building, destroying the Lovell building. For a period of two years or so, Petranek's operated at 519 North Milwaukee Avenue while the building in the photograph was erected. Petranek's reopened at 426 North Milwaukee Avenue in 1956. Lou Petranek left in 1960. A series of owners took over, keeping the name Petranek's and operating as the only independent pharmacy in the area. Also pictured in this photograph are Mooney's Fur Shop (428 N. Milwaukee Ave.), Enevold Realty Company (430 N. Milwaukee Ave.), and Morrison Shoes (432 N. Milwaukee Ave.)."
Other Sources
Sanborn Maps--1948 (Sheet 2)
Historic photos from the 1950s and 1970s on Illinois Digital Archives (in collection of the Libertyville-Mundelein Historical Society and Cook Memorial Public Library)--
http://www.idaillinois.org/cdm/singleitem/collection/cookmemo11/id/2031/rec/2
http://www.idaillinois.org/cdm/singleitem/collection/cookmemo11/id/6641/rec/3