In the 19th century, definiteness in the plural could be marked with two different articles, -na and -ne, but the norms regulating the variation were not universally agreed upon. In this study, I investigate how 19th-century Swedish grammars approach the variation in suffixes and how the prescriptive norms match the language used in Swedish-language newspapers from the same era, with special attention given to the differences between the varieties of Swedish spoken in Sweden and Finland. For this purpose, two historical newspaper corpora were consulted, comprised of newspapers published during the 19th century in Sweden and Finland, respectively. The findings show that from the middle of the 19th century, the grammars are generally split into two practices, with one attributing the use of the articles to the declension of the noun, while the other, mainly associated with the historical-comparative school, attributing it to the grammatical gender of the noun. In addition, grammars written in Finland stress the semantic gender of animate nouns. This difference is also reflected in the corpora: while both varieties are influenced by both the gender and the declension, the declension is the most important factor in the Swedish corpora, whereas semantic gender is the main factor in the Finnish corpora.