Please add any more information that you know about him from the United States, otherwise it is very difficult to make that jump back over the ocean to Norway.
Is this your Ernst? name: Ernst Aleksander Rosenlund event: Draft Registration event date: 1942 event place: Fort Worth, Tarrant, Texas gender: Male birth date: 20 Jan 1884 nara publication title: World War II Draft Cards (4th Registration) for the State of Texas nara publication number: arc identifier: 576252 film number: 4147855 digital folder number: 004147855 image number: 02708
If so, I found his emigration from Oslo, Norway in 1905
251873 Oslo1905Mars10Ernst AlexanderRosenlundmugmøllearb.21KristianiaS. Dakotafarmera.M. R. RaffelMontebello (leaving Oslo March 10, 1905, Ernst Alexander Rosenlund, male, unmarried mill worker, age 21 (born about 1884) from Oslo, (Kristiania( going to South Dakota to be a farmer.Someone in the family probably sponsored him to come over.)
If this is not your Ernst, please include some information from the USA that might help.Places where he lived, anything.
It is possible that he took the name Rosenlund after coming here.Do you have him on any censuses that tell when he came to the USA?
Is this him on the 1940 census? https://familysearch.org/pal:/MM9.1.1/K47X-MSY
name: Ernest Rosenlund titles & terms: event: Census event year: 1940 event place: Ward 10, Fort Worth, Justice Precinct 1, Tarrant, Texas, United States gender: Male age: 56 marital status: Married race (original): race (standardized): White relationship to head of household (original): relationship to head of household (standardized): Head birthplace: Norway estimated birth year: 1884 residence in 1935: Same Place enumeration district number: 257-65 family number: 136 sheet number and letter: 61A line number: 21 nara publication number: T627 nara roll number: 4186 digital folder number: 005458100 image number: 00072 Household Gender Age Birthplace headErnest RosenlundM 56 Norway wifeEmma RosenlundF 46 South Dakota sonArleigh RosenlundM 15 Texas
name: E A Rosenlund event: Census event date: 1930 event place: Fort Worth, Tarrant, Texas gender: Male age: 47 marital status: Married race: White birthplace: Norway estimated birth year: 1883 immigration year: 1902 relationship to head of household: Head father's birthplace: Norway mother's birthplace: Norway enumeration district number: 0028 family number: 1085 sheet number and letter: 67A line number: 20 nara publication: T626, roll 2393 film number: 2342127 digital folder number: 4547372 image number: 00710 Household Gender Age Birthplace headE A RosenlundM 47 Norway wifeEmma RosenlundF 37 South Dakota sonArleigh RosenlundM 5 Texas roomerAgnes HutchersonF 14 Texas
NOte how the immigration year is given as 1902, but I found it in Norway on 1905.