I first took a look at the Domelle's in the 1940 census back in 2012, so it's due for an update based on new information I have.
It's not a common name and does have many spelling variations in the US, including:
The rarity of the name has always led me to believe that any Domelle out there is likely sourced from the same line that originated in the Alsace-Lorraine region as "Tomule".
Today I looked in the 1940 US Federal census for any occurrence of a surname of Domelle, Domele or Dumelle, especially for those with a birthplace of Hungary, Indiana or Illinois since those are the main locations for the initial immigrant families.
Here is what I found:
1) There are 10 households of Domelles in the US in 1940 (6 Domelles, 3 Domeles and 1 Dumelle). There could be 1 or 2 more but they are currently spelled in such a way that I couldn't nail them down. I might figure them out later. :-)
2) 5 of them are in the northwest corner of Indiana (4 in Newton County, 1 in Lake County).
2a. William Domelle, his wife and adult son lived on a farm in Lincoln, Newton County, Indiana. William is brothers with 2b. William is the 2nd cousin 1x removed of 3c. William's sons are 2c and 4a, and his daughter is 3a.
2b. Nick Domelle (William's brother) and his wife lived on a farm in Lincoln, Newton County, Indiana. They are listed on the next lines of the census form under 2a, his brother. Nick is the 2nd cousin 1x removed of 3c.
2c. Pete Domelle (spelled incorrectly as Domella in the census record), his wife and baby daughter lived in Hammond, Lake County, Indiana. He is the son of 2a and brother to 3a and 4a.
2d. John Domele and his wife lived on a farm in Lake Township, Newton County, Indiana. John is 1st cousins with 2a and 2b.
2e. Tony Domele, his wife and 2 children lived on a farm in Lake Township, Newton County, Indiana and is listed just a few lines down on the census from his parents, 2d. His deceased brother's widow and child are 3d.
3) 4 of them are in Chicago, Illinois (not far from the northwest corner of Indiana - also 2 of those were young Domelle ladies on their own in the big city).
3a. Mary Domelle (spelled incorrectly as Donnelly in the census record) lived as a lodger at 510 North Lavergne Ave, Chicago, Illinois. She is the daughter of 2a and the sister of 4a.
3b. Betty Domelle lived as a lodger at 2940 W. 54th St, Chicago, Illinois. She is the daughter of 2b.
3c. Peter Dumelle, his wife and 6 children lived at 3442 N. Halsted St, Chicago, Illinois. Frank is the 2nd cousin of 2a and 2b.
3d. Clara Domele, widow of Martin Domele, and their son lived at 1616 Nelson St, Chicago, Illinois. Martin is the son of 2d and brother to 2e.
4) 1 of them, my direct ancestor, wandered over to Tompkins County, New York (thank goodness since that's where he met my grandmother!).
4a. William Domelle, son of 2a above, and brother to 3a, lived as a hired man on a farm at Kline Road, Lansing, Tompkins County, New York. He is the brother of 2c and 3a.
Below is a map showing the distribution. Just one big cluster except for the 1 outlier over in NY.
Originally all the Domelles/Domeles were in Chicago, but the 2 brothers and their cousin moved just south to Indiana to farm.