Łomża Department
Łomża Department was an administrative division and local government in the Polish Duchy of Warsaw in the years 1807–15. The Department comprised 10 counties and had its capital at Łomża.
From January to July 1807 the Department was known as the Białystok Department, with its capital at Białystok. However, after the Treaties of Tilsit, the Russian Empire agreed to the creation of the Duchy of Warsaw; but in exchange the Department ceded four counties: Białostocki, Bielski, Sokólski, and Drohicki. Thus the Department's capital had to be moved, and its name was accordingly changed to that of the new capital, Łomża.
After 1815 most of the Łomża Department's territory became part of Augustów Province. In 1867 it was reconstituted as the Łomża Governorate.It was divided into 7 counties:
