I-485轉到LOCAL

我先生的i-485在幾天前剛剛通過。今天我受到uscis的e-mail，說我的case轉到了local office：

on july 21, 2006, we transferred your i485 application to register permanent residence or to adjust status to an office in xxx for processing. our office in xxx will send you a written decision as soon as processing is complete. you should receive a notice ining you that your case has been transferred to a local office.

謝謝大家的回答。我在明尼蘇達州。我查詢了以前的帖子，我的好像與別人不同：
隻是說原因是為了processing. our office in Minnesota will send you a written decision。並沒有提麵試的事情。
轉到LOCAL的原因到底有哪些呢？是不是一定會麵試呢？麵試前會發通知嗎？通知上會寫需要什麽材料嗎？配偶的I-485經常會轉到LOCAL嗎？如果沒有音信，就這麽等嗎？謝謝。