As writes Paweł Dudek of PAN (Pracownia Toponomastyczna Instytutu Języka Polskiego, Toponymical Department of the Institute of the Polish Language), the endings -ów and -ew are "among the most productive suffixes for forming possessive names, indicating the founder or owner of an area. They also exist in the feminine with -owa and -ewa (for example, Limanowa, Wiśniewa) and the neuter with -owo and -ewo (for example, Wielichowo, Radzewo)."
"Throughout the course of time, the grammatical type and number changes often (for example, Pniewo - Pniewy)," continues Dudek. "Names with the suffix -ów dominate in Lesser Poland [south-eastern Poland], and names with -owo in Greater Poland [central north-western Poland]. Names ending with -owa are characteristic of southern Lesser Poland, especially in Podhale." He explains that the geographic distribution of the suffix disparity confirms an old dialectal boundary, which means that in northern Poland, names ending with -owo/-ewo changed their form to -ów/-ew later.