A seventeenth century Scandinavian
man by the name of Jonas Bronck immigrated in 1639 to New Amsterdam
(now New York), which was right next to the Bronx River, that was
later named after him.
Jonas owned a 680 acre farm called 'Bronck’s Land' and the river
abutting it 'Bronck’s River'. Various people owned this property and
kept the name, until Colonel Lewis Morris acquired it and renamed it
the 'Manor of Morrisania'. The river next to it continued to be
called Bronck’s River. From the river’s name, the modern-day name of
'Bronx' extended to the region directly around it.
The spelling change happened around the same time there was a big
push for the simplification of English, such as thre names of the
Boston Red Sox and the Chicago White Sox, from 'Socks'.