It has not been so easy to work out the origins of the ELWICK's in America. The 1880 Census shows just 41 individuals with the name, of these:-
Some of my family migrated from England to Canada and then into the United States of America and account for 16 of the 41.
A Simpson ELWICK and his mother both born in Durham England account for another 2.
Those of Nordic origins are probably derived from the name ELVIK.
A George ELWICK emigrated to US in 1850 (leaving his wife and children in England!!) and could have started another family. He is not on this or the 1900 Census so could have died.
A John ELWICK emigrated from Durham to Illinois in 1852, and is found in the 1870, 1880 and 1900 Census living in Decorah Iowa with a family of 6.
Twenty years later in the 1900 Census there are 99 people with the name ELWICK of these:-
My family accounts for 25 of the 99
The above named John ELWICK accounts for 14 of the 99
Of the remainder another 14 were born in West Virginia and I believe they are actually ELSWICK's which is a common name in that area. It could have been ELWICK originally as a John ELWICK travelled to Virginia from London between Sep 19 - Oct 16 1684 and his brother James regularly traded between the 2 countries.