The Guarani language is co-official with Spanish in Paraguay, and the country's unique history has caused Guarani to have a major influence on pronunciation, tone, and other characteristics of Spanish. This influence is not homogenous, however; the Spanish spoken in rural areas tends to have a more apparent Guarani influence, for example. The use of Spanish is most prevalent in cities and officialdom.
The unique features of Paraguayan Spanish developed in part due to Paraguay's early isolation; for example, José Gaspar Rodríguez de Francia, the country's president until 1840, sealed Paraguay's borders. Other experiences with geographic, political, and economic isolation relative to its neighbours allowed Spanish spoken in Paraguay to develop its own unique characteristics, even apart from the wide-ranging influence of Guarani.
Paraguayan Spanish shares many similarities with Rioplatense Spanish (that is, the variety spoken in Argentina) such as the use of the voseo and various words and phrases.