In the era of the partitions, Ciechanowiec was passed onto Prussia, and after the Congress of Vienna to the Russian Empire. Later the city was divided into two parts: right bank (called New Town or "Polish section"), was part of the Polish Kingdom and the left bank Old Town ("Rus section") in Russia. As a result of the November and January Uprisings, the right bank of Ciechanowiec lost the city rights in 1870. At the end of the nineteenth century, the textile industry rapidly developed in the city. Ciechanowiec was also very popular for various horse fairs. Significant damage from the times of World War I and the Polish–Soviet War were slowly repaired in the interwar period.