WP meaning in Regional ?

The Province of West Prussia (German: Provinz Westpreußen; Kashubian: Zôpadné Prësë; Polish: Prusy Zachodnie) was a province of Prussia from 1773 to 1829 and 1878 to 1919. West Prussia was established as a province of the Kingdom of Prussia in 1773, formed from Royal Prussia of the Polish–Lithuanian Commonwealth annexed in the First Partition of Poland. West Prussia was dissolved in 1829 and merged with East Prussia to form the Province of Prussia, but was re-established in 1878 when the merger was reversed and became part of the German Empire. From 1918, West Prussia was a province of the Free State of Prussia within Weimar Germany, losing most of its territory to the Second Polish Republic and the Free City of Danzig in the Treaty of Versailles. West Prussia was dissolved in 1919, and its remaining western territory was merged with Posen to form Posen-West Prussia, and its eastern territory merged with East Prussia as the Region of West Prussia district.

West Prussia's provincial capital alternated between Marienwerder (present-day Kwidzyn, Poland) and Danzig (Gdańsk, Poland) during its existence. West Prussia was notable for its ethnic and religious diversity due to immigration and cultural changes, with the population becoming mixed over the centuries. Since the early Middle Ages the region was inhabited by numerous Slavic and Baltic peoples, such as Pomeranians in the Pomerelia region, Old Prussians and Masovians in Kulmerland, and Pomesanians east of the Vistula River. Later Germans followed. Germans were also the largest group in West Prussia since the middle of the 19th century until its dissolution in 1919, with large numbers of ethnic Poles, Kashubians, Mennonites, and Jews also settling in the region.