According to a USCIS Update, effective December 10, 2007, USCIS will only accept H-2A
(temporary/seasonal agricultural worker) petitions mailed or delivered to its California Service Center.

The notice informs the public to use the following addresses:
Direct mail:
U.S. Citizenship and Immigration Services California Service Center
ATTN: H-2A Processing Unit
P.O. BOX 10140
Laguna Niguel, CA 92607-1040
Non-United States Postal Service deliveries (e.g. private couriers):
U.S. Citizenship and Immigration Services California Service Center
ATTN: H-2A Processing Unit
24000 Avila Road, Room 2312
Laguna Niguel, CA 92677