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| ATLANTIC DAWN LIMITED | — | 19951867 D | 1995-03-13 | Active | PORTLAND |
| ATLANTIC DEFENSE CONSTRUCTORS, LLC | — | 20070195DC | 2006-07-20 | Active | BANGOR |
| ATLANTIC DEFENSE ENGINEERING, LLC | — | 20063756DC | 2005-05-25 | Dissolved | OLD TOWN |
| ATLANTIC DEFENSE INDUSTRIAL, LLC | — | 20083771DC | 2008-06-02 | Dissolved | BANGOR |
| ATLANTIC DENTAL HYGIENE LLC | — | 202506587DC | 2024-10-10 | Active | WARREN |
| ATLANTIC DESIGN AND RESEARCH, INC. | — | 19841202 D | 1984-02-10 | Suspended | DEXTER |
| ATLANTIC DESIGN, INC. | — | 202600342 F | 2025-09-15 | Active | CHELSEA |
| ATLANTIC DESIGNS INTERNATIONAL, LLC | — | 20071580DC | 2006-12-08 | Dissolved | RUMFORD |
| ATLANTIC DESIGNS KITCHEN & BATH CABINETERY TAKE US FOR GRANITE | — | 20090054M | — | | |
| ATLANTIC DESIGNS, INCORPORATED | — | 19981266 D | 1998-01-02 | Dissolved | BANGOR |
| ATLANTIC DEVELOPERS | — | 19981445 D | 1998-01-23 | Active | OLD ORCHARD BEACH |
| ATLANTIC DEVELOPMENT, LLC | — | 20042586DC | 2004-04-22 | Canceled | PORTLAND |
| ATLANTIC DIAGNOSTICS, LLC | — | 20080683DC | 2007-09-06 | Dissolved | WESTBROOK |
| ATLANTIC DINER CORPORATION | — | 20021779 D | 2002-03-26 | Dissolved | SOUTH PORTLAND |
| ATLANTIC DISTRIBUTORS, INC. | — | 19872812 D | 1987-05-11 | Suspended | PORTLAND |
| ATLANTIC DIVERSIFIED COMPANIES, INC. | — | 19860980 D | 1985-11-21 | Suspended | |
| ATLANTIC DIVERSIFIED, INC. | — | 20000165 D | 1999-07-28 | Dissolved | STANDISH |
| ATLANTIC DOCK COMPANY, L.L.C. | — | 19970240DC | 1997-02-12 | Active | STONINGTON |
| ATLANTIC DOOR SERVICES, LLC | — | 20238192DC | 2022-09-27 | Active | RAYMOND |
| ATLANTIC DRIFT LLC | — | 202601218DC | 2025-07-02 | Dissolved | TOPSHAM |
| ATLANTIC DRILLING & BLASTING, INC. | — | 19851397 D | 1985-03-06 | Suspended | SCARBOROUGH |
| ATLANTIC DRIVING SCHOOL OF MAINE | — | 19920896 D | 1991-12-06 | Dissolved | LEWISTON |
| ATLANTIC DRYWALL, INC. | — | 19871348 D | 1986-12-22 | Active | YORK |
| ATLANTIC DUNCANS INTERNATIONAL, INC. | — | 20000046 F | 1999-07-19 | Withdrawn | AUGUSTA |
| ATLANTIC EARTH WORKS, LLC | — | 20182258DC | 2017-10-30 | Dissolved | SACO |
| ATLANTIC EAST APPRAISALS, INC. | — | 20140999 D | 2014-04-28 | Active | JONESPORT |
| ATLANTIC ECOTECHNOLOGIES, INC. | — | 19941046 D | 1993-12-10 | Suspended | PORTLAND |
| ATLANTIC EDGE, LLC | — | 20252077DC | 2023-10-30 | Active | EDGECOMB |
| ATLANTIC ELECTRICAL SERVICES, LLC | — | 20238115DC | 2022-10-03 | Active | LYMAN |
| ATLANTIC ELEVATOR INSPECTION SERVICE, INC. | — | 19900391 D | 1989-08-31 | Active | PORTLAND, |
| ATLANTIC ENDEAVORS, INC. | — | 20051215 D | 2004-12-28 | Dissolved | TOPSHAM |
| ATLANTIC ENERGY PARTNERS LLC | — | 19990902DC | 1999-06-09 | Canceled | AUGUSTA |
| ATLANTIC ENGINE AND PARTS COMPANY, INC. | — | 19820404 D | 1981-09-23 | Dissolved | PORTLAND |
| ATLANTIC ENGINE COMPANY NO. 2 | — | 19960094ND | 1995-09-14 | Active | CAMDEN |
| ATLANTIC ENGINEERING GROUP, LLC | — | 20240764FC | 2023-11-15 | Withdrawn | AUGUSTA |
| ATLANTIC ENGINEERING SERVICES INC. | — | 19862295 D | 1986-04-25 | Dissolved | FALMOUTH |
| ATLANTIC ENTERPRISES LLC | — | 20201708DC | 2019-09-13 | Active | MACHIAS |
| ATLANTIC ENTERPRISES LLC | — | 20090147DC | 2008-07-16 | Dissolved | GORHAM |
| ATLANTIC ENTERPRISES, INC. | — | 19790473 D | 1978-10-10 | Dissolved | ELLSWORTH |
| ATLANTIC ENVIRONMENTAL CONTRACTORS, INC. | — | 20140068 D | 2013-07-25 | Active | LEWISTON |
| ATLANTIC ENVIRONMENTAL LLC | — | 20173596DC | 2017-02-02 | Dissolved | WOOLWICH |
| ATLANTIC ENVIRONMENTAL SERVICES, INC. | — | 19920511 D | 1991-09-27 | Suspended | ARUNDEL |
| ATLANTIC EQUIPMENT LEASING, INC. | — | 19870275 D | 1986-07-16 | Suspended | |
| ATLANTIC EQUIPMENT RENTAL, L.L.C. | — | 20140464DC | 2013-08-07 | Dissolved | HANCOCK |
| ATLANTIC EQUITY GROUP, INC. | — | 19831389 D | 1983-03-31 | Suspended | PORTLAND |
| ATLANTIC EVENTS & CATERING, INC. | — | 20071022 D | 2007-01-08 | Dissolved | PORTLAND |
| ATLANTIC EXECUTIVE ENTERPRISES INC | — | 20220021 D | 2021-07-16 | Active | BANGOR |
| ATLANTIC EXPORTS, INC. | — | 19961413 D | 1996-01-09 | Suspended | WINSLOW |
| ATLANTIC EXPOSURE CRUISE & CHARTER, LTD. | — | 19981597 D | 1998-02-17 | Dissolved | KENNEBUNK |