had over 10 million members, which became the largest union membership in the world. During the Communist era, the 38 regional delegates were arrested and jailed when martial law came into effect on 13 December 1981 under General Wojciech Jaruzelski. After a one-year prison term the high-ranking members of the union were offered one way trips to any country accepting them (including Canada, the United States, and nations in the Middle East). Solidarity was organized as an industrial union, or more specifically according to the One Big Union principle, along the lines of the Industrial Workers of the World and the Spanish Confederación Nacional del Trabajo (workers in every trade were organized by region, rather than by craft). In 2010, Solidarity had more than 400,000 members. National Commission of Independent Self-Governing Trade Union is located in Gdańsk and is composed of Delegates from Regional General Congresses. Regional structure Solidarity is divided into 37 regions, and the territorial structure to a large degree reflects the shape of Polish voivodeships, established in 1975 and annulled in 1998 (see: Administrative division of People's Republic of Poland). The regions are: Gdańsk, based in Gdańsk Warmia-Masuria, based in Olsztyn Elbląg, based in Elbląg Lower Silesia, based in Wrocław Pila, based in Piła Western Pomerania, based in Szczecin Land of Łódź, based in Łódź Częstochowa, based in Częstochowa Land of Sandomierz, based in Stalowa Wola Płock-Kutno, based in Płock Lesser Poland, based in Kraków Opole Silesia, based in Opole Seashore, based in Koszalin Słupsk, based in Słupsk Zielona Góra, based in Zielona Góra Podbeskidzie, based in Bielsko-Biała Konin, based in Konin Southern Greater Poland, based in Kalisz Podlachia, based in Białystok Piotrków, based in Piotrków Trybunalski Cuiavia and Dobrzyń Land, based in Włocławek Carpathia, based in Krosno Land of Rzeszów, based in Rzeszów Toruń, based in Toruń Silesia-Zaglebie, based in Katowice Land of Radom, based in Radom Greater Poland, based in Poznań Gorzów, based in Gorzów Wielkopolski Holy Cross, based in Kielce Middle-East, based in Lublin Bydgoszcz, based in Bydgoszcz Jelenia Góra, based in Jelenia Góra Leszno, based in Leszno Chełm, based in Chełm Przemyśl-Jarosław, based in Przemyśl Mazovia, based in Warsaw Copper Basin, based in Legnica Network of key factories The network of Solidarity branches of the key factories of Poland was created on 14 April 1981 in Gdańsk. It was made of representatives of seventeen factories; each stood for the most important factory of