If you are referring to I-485 filing then the place where you live determines the service center.
NSC :
Alaska, Arizona, California, Colorado, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, North Dakota, Ohio, Oregon, South Dakota, Utah, Washington, Wisconsin, Wyoming, Guam or the Commonwealth of the Northern Mariana Islands
TSC:
Alabama, Arkansas, Connecticut, Delaware, District of Columbia, Florida, Georgia, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Mississippi, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Pennsylvania, Puerto Rico, Rhode Island, South Carolina, Oklahoma, Tennessee, Texas, Vermont, Virginia, U.S. Virgin Islands, or West Virginia
Detailed here :
http://www.uscis.gov/i-485-addresses