USA
From Germany to the USA
According to my researches, all Callenius families living in the USA today descend from German immigrants.
Largest Callenius Family in the USA
One of the largest, or the largest, family communities – centered in Iowa – descends from the emigrant Adolph Friedrich Callenius. He was born on June 3, 1834, in Dorum, the son of Otto Christian Ludewig Callenius and Anna Elisabeth Heynsohn, and is thus the grandson of the founding father of the German Dorum line, Otto Ludwig Callenius (1752–1828).
Here is the baptismal record of the Dorum parish from 1834:

Adolf Friedrich Callenius emigrated to the USA around 1860, where he married Metta Eggers (his presumably first child, George H. Callenius, was born July 30, 1861 in New York). He lived a short time in Illinois (1865) and finally settled in Baker, O’Brien, Iowa, also in 1865. In the USA, he called himself “Adolph William Callenius” or “Adolph F. L. Callenius.” He died on June 2, 1914 (gravestone) in Primghar, O’Brien, Iowa.
As far as I could research, Adolph had three sons and one daughter: George H. Callenius (*1861), Otto F. L. Callenius (*1862), and William Callenius (*1873/74), and Annie Callenius (*1867). A respectable number of descendants still live today. Almost all Calleniuses living in Iowa today are descended from them.
Other Emigrants to the USA
There are other emigrants to North America listed in various files and emigration lists. For example,
Carl F. Callenius: from Germany, he obtained American citizenship in 1856 and lived in New York.
Theodor Callenius: The merchant, born in 1840, arrived on Ellis Island by ship from Bremen on March 27, 1865.
Jacob Callenius: Born in 1832, he later became a physician. He arrived by ship in 1867 and settled there. He lived in Massachusetts in 1880 and then in Allegheny, Pennsylvania, in 1900.
Jacob Callenius: Another Jacob, born in 1835, immigrated to the USA in 1871.
Nathan or Nathan William Callenius: Immigrated in 1883. Both parents were from Germany.
William Callenius: Born in 1858, he immigrated to East Feliciana, Louisiana, in 1883. He was said to be from Hesse.
Michael J. Callenius: He is said to have immigrated to the USA in 1885 and was born around 1870.
Hermann Alexander Callenius: He arrived in the USA in 1896 at the age of 14 and became a US citizen in 1902. Both his parents were from Germany.