The Westphalian dialect region includes the north-eastern part of North Rhine-Westphalia, i.e. the former Prussian province of Westphalia, without Siegerland and Wittgenstein, but including the southern part of former government district Weser-Ems (e.g. the region around Osnabrück and the landscape of Emsland in modern Lower Saxony).
This accent, however, does not stand out as much as for example Bavarian, because Westphalia is closer to the Hanover region, whose speech variety is generally considered to be standard modern German.
One of the reasons for the diminishing use of Westphalian in Germany is the rigorous enforcement of German-only policies in traditionally Low German-speaking areas during the 18th century.
In an extreme case, Hannover and its hinterland were forced to adopt rather unnaturally a form of German based on the written standard.
Examples include Pölter [ˈpœltɐ] "pyjamas/pajamas", Plörre [ˈplœʁə] "dirty liquid", and Mötke [ˈmœtkə] "mud, dirt".