Mizil reached its peak of activity during the 19th century, rapidly outpacing Urlați, which had possessed the advantage of having the closest market to most of the towns in that part of Wallachia. Moreover, in 1847 the Ploiești-Buzău road began to be built along the foothills, shortening and modernising the link between the capitals of the Danubian Principalities, Bucharest and Iași. It was from the latter to the former city that Alexandru Ioan Cuza passed through Mizil in 1859, on his way to become head of the United Principalities. In this period, inhabitants worked in agriculture, viniculture, animal husbandry and various trades. The first school was built in 1857, by the "boyar" Ion Căciunescu, although teaching had begun around 1838. Following the efforts of mayor Leonida Condeescu, an elementary trade school was established about 1902, with a high school opening later.