According to this page describing German dialects spoken in Kansas, the latest wave of immigration of German-speakers to Kansas is coming from...Mexico:
For over a decade, farm laborers and their families from Mennonite colonies in Chihuahua province in northern Mexico have been migrating into the market of southwestern Kansas. These people are Low German-speaking Old Colony Mennonites who immigrated to Canada from southern Russian in the late nineteenth century. After the First World War, they moved to new colonies in Mexico to avoid restrictions being placed on them by the Canadian authorities. Now as the economic conditions in Chihuahua deteriorate they are seeking better opportunities for their families.... The high demand in southwestern Kansas for agricultural labor is drawing them to Kansas.... The need for cheap labor in the feed lots is overwhelming and with the Spanish-speaking Mexicans that flock to this labor market come Plautdietsch-speaking Mennonites as well.
Today ... we estimate that some 5,000 Mennonites from Mexico are living in the southwestern counties of Kansas. These are young families with children. At home the language of everyday use is Plautdietsch. The church congregations established by these new immigrants vary in their language use. In November 2003, we experienced a two-hour worship service at the Gospel Mennonite Church in Copeland, Kansas. All preaching was in Low German; hymn singing and Bible passages in literary German; one closing hymn was sung in English. In other congregations, the use of English for preaching has been reported. Schools operated by these Mennonites are conducted in English. All schools, whether Mennonite or public, must deal with large numbers of children requiring ESL classes as they enter the school system. It can be overwhelming for a teacher in first grade to be confronted with half of the class consisting of Low German-speaking children. The Kansas Department of Health and Environment also reports that fully one-third of its low income health contacts are with these Low German-speaking Mennonites in southwestern Kansas.