As an immigration lawyer I subscribe to receive automated e-mails sent out by the U.S. Citizenship and Immigration Service. Just yesterday I received an e-mail titled "Did you Know? The INS No Longer Exists". Apparently, despite the INS not existing since 2003, each month tens of thousands of visitors to the USCIS website find it by googling "INS". I'm an immigration lawyer, and not a marketing expert, but this seems like poor branding when eight years later tens of thousands of people still refer to you by your former name. Even worse, when I google "INS" the USCIS is not even at the top of the page. Now, eight years later, the USCIS is wondering why so many of us still don't know the name of their agency. I personally think it's a name flow problem. INS just rolls off the tongue rather smoothly. If you slur the letters together, it could really be just about two syllables. And no one ever felt the need to call it by its long form "Immigration and Naturalization Service". Everyone just knew (and still does know) what the INS was. "USCIS" just lacks the flow of "INS". You can't slur the letters so easily, and it's five distinct syllables. And "United States Citizenship and Immigration Service" is simply a mouthful to say, let alone remember. When an agency begins with "United States", people start to zone out after hearing the first two words as they know it's some government bureaucratic agency.
My personal recommendation is to first shorten it to three letters, along the lines of IRS, FBI, CIA. Everyone knows them by their abbreviation. Then, "CIS" seems like the obvious choice except it makes too much of a hissing sound when said quickly. Which leads me to my actual recommendation: "ICS", short for Immigration and Citizenship Service. It's got the three letters, it's descriptive, and it's easy and catchy to say. I think it could catch on in faster time than eight years.