"How do you report suspected illegal aliens???"

http://reportanillegalalien.com/

What can I do?

Be that as it may, a private citizen is not required to report someone who is in the country unlawfully, nor does the United States Immigration and Custom Enforcement (USICE) prefer it done. The USICE and FBI are quite aware that persons report foreign nationals for personal reasons rather than security and may seem a bit irritated if such is the case. The obvious exception is if the person has committed or is committing a criminal offense such as domestic and/or child abuse, assault, robbery, and so forth. Or equally important, if the person gives the impression of being a threat or potential threat to national and society's security/safety, (a terrorist). This should not deter a private citizen from taking action, if done properly and responsibly.

However, if you wish to report a person(s) you may do so by calling United States Immigration and Customs Enforcement (USICE) at 1-866-347-2423. It is advisable to contact the local ICE Field Office for a faster response. Most of the time if you call the main number, they will refer you to your local field office. For a listing of ICE field offices click HERE

This is their telephone number.  1-866-DHS-2-ICE

This is their web site's url. On it you'll find a contact button.  http://www.ice.gov/

If you dig around for a bit, you'll find this list of field offices.   http://www.ice.gov/about/dro/contact.htm

Contact the nearest field office to you.

Field Offices

Raymond Simonse, Field Office Director
180 Spring Street SW
Atlanta, GA 30303
Phone: (404) 893-1210
Area of Responsibility: Georgia, North Carolina, South Carolina

Calvin McCormick, Field Office Director
31 Hopkins Plaza, 7th Floor
Baltimore, MD 21201
Phone: (410) 637-4000
Area of Responsibility: Maryland

Bruce Chadbourne, Field Office Director
10 New England Executive Park
Burlington, MA 01803
Phone: (781) 359-7500
Area of Responsibility: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, Vermont

Michael T. Phillips, Field Office Director
130 Delaware Avenue
Buffalo, NY 14202
Phone: (716) 551-4741 ext. 2535
Area of Responsibility: Upstate New York

Glenn Triveline, Acting Field Office Director
101 W. Congress Pkwy, Suite 4000
Chicago, IL 60605
Phone: (312) 347-2400
Area of Responsibility: Illinois, Indiana, Kansas, Kentucky, Missouri, Wisconsin

Nuria T. Prendes, Field Office Director
8101 N. Stemmons Frwy
Dallas, TX 75247
Phone: (214) 905-5860
Area of Responsibility: North Texas, Oklahoma

John Longshore, Field Office Director
4730 Paris Street
Denver, CO 80239
Phone: (303) 371-1067
Area of Responsibility: Colorado, Wyoming

Vincent J. Clausen, Field Office Director
333 Mt. Elliott St.
Detroit, MI 48207
Phone: (313) 568-6049
Area of Responsibility: Michigan, Ohio

Robert E. Jolicoeur, Field Office Director
1545 Hawkins Blvd
El Paso, TX 79925
Phone: (915) 225-1901
Area of Responsibility: West Texas, New Mexico

Kenneth L. Landgrebe, Field Office Director
126 Northpoint Drive
Houston, TX 77060
Phone: (281) 774-4968
Area of Responsibility: Southeast Texas

Brian M. DeMore, Field Office Director
300 North Los Angeles St., Room 7631A
Los Angeles, CA 90012
Phone: (213) 830-7911
Area of Responsibility: Central California

Michael D. Rozos, Field Office Director
Krome SPC
18201 SW 12th St
Miami, FL 33194
Phone: (305) 207-2001
Area of Responsibility: Florida, Puerto Rico, U.S. Virgin Islands

Scott Weber, Field Office Director
Peter W. Rodino Jr. Federal Building
970 Broad Street, Room 904
Newark, NJ 07102
Phone: (973) 645-3666
Area of Responsibility: New Jersey

George H. Lund III, Field Office Director
DHS/ICE 1250 Poydras Suite 325
New Orleans, LA 70113
Phone: (504) 599-7800
Area of Responsibility: Alabama, Arkansas, Louisiana, Mississippi, Tennessee

John Tsoukaris, Acting Field Office Director
26 Federal Plaza, Rm. 1104
New York, NY 10278
Phone: (212) 264-4213
Varick Street Facility: (212) 863-3401
Area of Responsibility: The five boroughs (counties of NYC) and the following counties:
Duchess, Nassau, Putnam, Suffolk, Sullivan, Orange, Rockland, Ulster, and West Chester

Thomas R. Decker, Field Office Director
1600 Callowhill St., 6th Floor
Philadelphia, PA 19130
Phone: (215) 656-7164
Area of Responsibility: Delaware, Pennsylvania, West Virginia

Katrina S. Kane, Field Office Director
2035 N. Central Avenue
Phoenix, AZ 85004
Phone: (602) 257-5900
Area of Responsibility: Arizona

Steven M. Branch, Field Office Director
5272 S. College Drive
Suite 100
Salt Lake City, UT 84123
Phone: (801) 313-4260
Area of Responsibility: Utah, Idaho, Montana, Nevada

Adrian R. Ramirez, Acting Field Office Director
8940 Fourwinds Drive
San Antonio, TX 78239
Phone: (210) 967-7055
Area of Responsibility: Central South Texas

Robin Baker, Field Office Director
880 Front Street, #2232
San Diego, CA 92101
Phone: (619) 557-6343
Area of Responsibility: San Diego and Imperial County

Nancy Alcantar, Field Office Director
630 Sansome Street, Rm 590
San Francisco, CA 94111
Phone: (415) 844-5512
Area of Responsibility: Northern California, Hawaii, Guam

A. Neil Clark, Field Office Director
12500 Tukwila International Blvd., 4th Floor
Seattle, WA 98168
Phone: (206) 835-0650
Area of Responsibility: Alaska, Oregon, Washington

Scott Baniecke, Field Office Director
2901 Metro Dr., Suite 100
Bloomington, MN 55425
Phone: (952) 853-2550
Area of Responsibility: Iowa, Minnesota, Nebraska, North Dakota, South Dakota

Deborah Achim, Field Office Director
2675 Prosperity Avenue
Fairfax, VA 22031
Phone: (703) 285-6200
Area of Responsibility: District of Columbia and Virginia

With respect to employers hiring unlawful immigrants, both the Department of Labor and the Department of Homeland Security have jurisdiction over enforcement. Employers are required to keep I-9 forms on file for at least three years for audits. If something suspicious is found during an audit, the Department of Justice and/or the Treasury Department will be called in to take action. So, if you want to contact someone about an employer, try either or both the DOL  http://www.dol.gov/ and DHS   http://www.dhs.gov/index.shtm . 

...call your local authorities. They can then report to the Law Enforcement Support Center (LESC), which is operated by U.S. Immigration and Customs Enforcement (ICE), the largest investigative agency in the Department of Homeland Security (DHS). LESC is a single national point of contact that provides timely customs information and immigration status and identity information and real-time assistance to local, state and federal law enforcement agencies on aliens suspected, arrested or convicted of criminal activity. If you don't trust your local enforcement to handle it, you can always call ICE yourself, at 1-866-DHS-2-ICE.

Located in Williston, Vt., LESC operates 24 hours a day, 7 days a week, 365 days a year. The primary users of LESC are state and local law enforcement officers seeking information about aliens encountered in the course of their daily enforcement activities.

I'm not sure why you didn't find this with a simple google search. I entered the terms 'reporting immigration violations', and this was the first hit.

Goldie

At the bottom of the page is <contact us>. Click that call the number or send an e-mail to the e-mail address given (towards bottom of page.)

Not to bother.    There are around twelve million of them.    They comprise a large part of the landscapers, poultry eviscerators, roofers, and ditchdiggers.   They're doing jobs other folks won't do for minimum wage.   They pay federal, state, and social security taxes and are unlikely to ever get any services or retirement from what they've paid. 

There are about 3,750 of them for each federal immigration agent.   It costs several thousand dollars to evict just one person.   There is not the time nor personnel nor money nor courts nor plane tickets to evict even 10% of them.    Plus it takes them less than a week to get back in.

The minimum wage down south of the border is like 40 cents an hour, so the incentive to move north is great.  You're not going to slow down or stop them by even trying to identify them and ship them back.