In my advancing years, I become more cynical and skeptical of "government" or "historians" versions, and with that proviso, I submit the following from the Immigration and Naturalization Service (INS) 

American Names / Declaring Independence
by Marian L. Smith, INS Historian

Note the following story, which is a perfect specimen of a peculiar quality of the American mind, one bearing no small relation to Independence Day:

I have a friend who tells the story of her ancestor coming from one of the Slavic countries and he, of course, could speak no English. At Ellis Island when he was being processed and any question was asked, he would nod his head and smile. Since all he did was smile when they asked his name, the clerk wrote down 'Smiley' for his surname. That was the family surname from then on.

...The idea that an entire family's name was changed by one clerk--especially one at Ellis Island--is seldom supported by historical research and analysis.

American name change stories tend to be apocryphal, that is, they developed later to explain events shrouded in the mist of time. Given the facts of US immigration procedures at Ellis Island, the above story becomes suspect. In the story, the immigrant arrives at Ellis Island and a record is then created by someone who cannot communicate with the immigrant, and so assigns the immigrant a descriptive name. 

In fact, passenger lists were not created at Ellis Island. They were created abroad, beginning close to the immigrant's home, when the immigrant purchased his ticket. It is unlikely that anyone at the local steamship office was unable to communicate with this man. His name was most likely recorded with a high degree of accuracy at that time.

It is true that immigrant names were mangled in the process. The first ticket clerk may have misspelled the name (assuming there was a "correct spelling"--a big assumption). If the immigrant made several connections in his journey, several records might be created at each juncture. Every transcription of his information afforded an opportunity to misspell or alter his name. Thus the more direct the immigrant's route to his destination, the less likely his name changed in any way.

The report that the clerk "wrote down" the immigrants surname is suspect. During immigration inspection at Ellis Island, the immigrant confronted an inspector who had a passenger list already created abroad. That inspector operated under rules and regulations ordering that he was not to change the or identifying information found for any immigrant UNLESS requested by the immigrant, and unless inspection demonstrated the original information was in error. 

Furthermore, it is nearly impossible that no one could communicate with the immigrant. One third of all immigrant inspectors at Ellis Island early this century were themselves foreign-born, and all immigrant inspectors spoke an of three languages. They were assigned to inspect immigrant groups based on the languages they spoke. If the inspector could not communicate, Ellis Island employed an army of interpreters full time, and would call in temporary interpreters under contract to translate for immigrants speaking the most obscure tongues.

Despite these facts, the Ellis-Island-name-change-story (or Castle Garden, or earlier versions of the same story) is as American as apple pie (and probably as common in Canada).

Why?

The explanation lies in ideas as simple as language and cultural differences, and as complex as the root of American culture. We all know names have been Anglicized in America (even the word "Anglicized" has been Americanized!). As any kindergartener learns, we live in a world where people ask our name then write it down without asking us how to spell or pronounce that name. Immigrants in America were typically asked their name and entered in official records by those who had "made it" in America and thus were already English-speaking (i.e., teachers, landlords, employers, judges etc.). The fact that those with the power to create official records were English-speaking explains much about small changes, over time, in the spelling of certain names.

Many immigrants welcomed this change. Anyone from Eastern Europe, with a name LONG on consonants and short on vowels, learned that his name often got in the way of a job interview or became the subject of ridicule at his child's school. Any change that might smooth their way to the American dream was seen as a step in the right direction. Perhaps this was the case with Mr. Smiley. It was the case of another family from Russia, named Smiloff or Smilikoff, who emigrated to Canada at the turn of the century. By the time their son immigrated to the US in 1911, his name had become Smiley. But some name changes are not so easy to trace. Rather than a different spelling of the same-sounding name, an entirely new name was adopted. These are the most American stories of all.

"Who is this new man, this American?" asked de Toqueville. He was Adam in the Garden, man beginning again, leaving all the history and heartbreak of the Old World behind. The idea that what made America unique was the opportunity for man to live in a state of nature, a society of farmers whose perception of Truth is unfettered by ancient social and political conventions lies at the base of Jeffersonian democratic theory. The New World became a place for mankind to begin again, a place where every man can be re-born and re-create himself. In such circumstances, the adoption of a new name is not surprising. Nor is it surprising in the cases of immigrants who came to America to abandon a wife and family or to escape conscription in a European army. There were all kinds of reasons, political and practical, to take a new name.

A newspaper in California recently ran the story of a Vietnamese immigrant with a long, Vietnamese name so strange-looking to Anglo eyes. The young man came to this country and began to work and study. He began every day by stopping at a convenience store to buy a "bonus pak" of chewing gum. Chewing all those sticks of gum got him through long days of working several jobs and studying English at night. When he finally naturalized as a US citizen, he requested his name be changed to Don Bonus--the surname taken from the "Bonus Pak" and chosen to signify all his work and effort to become an American. He was a new man.

If not for the newspaper story, we would not understand this name change. Mr. Bonus' naturalization papers would simply record the name change but not the reasons behind it. If he had not naturalized, his Bonus family descendents generations from now would be at quite a loss to explain the origin of their name.

The documentation of name changes during US naturalization procedure have only been required since 1906. Prior to that time, only those immigrants who went to court and had their name officially changed and recorded leave us any record. 

Congress wrote the requirement in 1906 because of the well-known fact that immigrants DID change their names, and tended to do so within the first 5 years after arrival. Without any record, immigrants and their descendents are left to construct their own explanations of a name change. 

Often, when asked by grandchildren why they changed their name, old immigrants would say "it was changed at Ellis Island." 

People take this literally, as if the clerk at Ellis Island actually wrote down another name. But one should consider another interpretation of "Ellis Island." That immigrant is remembering his initial confrontation with American culture. 

Ellis Island was not only immigrant processing, it was finding one's way around the city, learning to speak English, getting one's first job or apartment, going to school, and adjusting one's name to a new spelling or pronunciation. All these experiences, for the first few years, were the "Ellis Island experience." When recalling their immigration decades before, many immigrants referred to the entire experience as "Ellis Island."

So, on this day when we celebrate the breaking of our bond with the Old World, let us welcome Mr. Smiley and all the new immigrants who will, in the next few years as they become Americans, make changes to their name which will confuse and confound their descendents for generations to come. 

INS History, Genealogy, and Education - American Names / Declaring Independence 
http://www.ins.usdoj.gov/graphics/aboutins/history/articles/NameEssay.html