Trevethan is a moderately common Cornish name and there were some 100 Trevethan families in Cornwall in 1891.  Trevathan is not a common Cornish name.  The census listed about 10 Trevathan families in 1891 but either their names were misspelled or they had no male descendants who remained in Cornwall because we have not been able to locate any Trevathans today who were born in Cornwall. In the U.S., Ancestry.com says that the approximate number of families were:                      Trevathan        Trevethan 1840                           5                      1                          1880                         120                  25       1920                         120                  35     As you can see, most of the Trevethans came to the U.S. iln the mid 19th century, primarily for mining work.  These numbers seem low for Trevathans; however it will take a careful review of the census to determine a more accurate number. In the 1990 U.S. census, Trevathan was the 19,915th most popular name (that is, there are 19,914 names that were more popular than Trevathan beginning witih Simth, Johnson, Williams, Jones, etc.).  The frequency of Trevathan is approximately .0005% of the population.  Based on a U.S. population of 300 million, that means roughly 1500 people have the Trevathan name today. Trevethan was the 76,969th most popular name with a frequency of approximately . 0001%.  That means roughly 300 people have the name Trevethan. Trevethan is often changed to Trevathan; but it seems that the reverse is rarely true: William Trevethan who came to the U.S. from Cornwall changed his name to Trevathan; and in over 300 years the name has remained as Trevathan with no instances of change back to Trevethan. The Trevethans who went from Cornwall to New Zealand changed their name to Trevathan. A Trevathan in Nevada in about 1900 and a Trevathan in Tennessee listed their birthplace as Cornwall.  Since there are so few known instances of Trevathan in Cornwall, they may have changed their name from Trevethan to Trevathan. Trevethan is often misspelled as Trevathan.  Tara Trevethan, owner of two restaurants in Florida, had the spelling of her name changed to Trevathan in this news story.
					This site assembled by Vernon Trevathan vernon@trevathan.info P. O. Box 37064, St. Louis, MO 63141 revised June 8, 2006 Copyright © 2006 Vernon L. Trevathan.  All rights reserved

Trevathan Genealogy - with focus on the U.S. and with connections to similar names worldwide
Trevathan or Trevethan, what's the difference?