| Mentone Residue and Gathering Pipelines | | TX | | |
| Mercer Compression Project | National Fuel Gas Supply Corporation | PA | | |
| Mercer Compressor Station | | | | |
| Miami Fort Generating Station CG25 Natural Gas Pipeline Project | Duke Energy Ohio | OH | | |
| MichCon Renaissance Line | Michigan Consolidated PL Co | MI | In service 2002 | |
| MichCon Sumpter Extension Pipeline Project | Michigan Consolidated PL Co | MI | In service 2009 | |
| Michigan/Ohio Pipeline Expansion | Buckeye Partners, LP | MI, OH, PA | In service 2016 | |
| Michigan/Ohio Pipeline Expansion Project (Phase II) | Buckeye Partners, LP | PA | | |
| Mid Michigan Pipeline - Phase 1 | | MI | 2023 | |
| Mid-Atlantic Connector Expansion Project | Transcontinental Gas Pipe Line Company, LLC | VA | 2011–2013 | |
| Mid-Atlantic Expansion Project | Texas Eastern Transmission, LP | PA | In service 2004 | |
| Mid-Continent Supply Header Interstate Pipeline Project | Midship Pipeline Company, LLC | | | |
| MidAmerican Des Moines Lateral | MidAmerican Energy Inc | IA | In service 2003 | |
| MidCoast System Alternative | | AL | In service 1997 | |
| MidWest PSI Energy Lateral Project 2000 IL-IN Segm | | IL, IN | In service 2001 | |
| Midcoast Energy Resource coastal use permit P20011176 pipeline | Midcoast Energy Resource | LA | | |
| Midcoast Energy Resources coastal use permit P20001840 pipeline | Midcoast Energy Resources Inc. | LA | | |
| Midcon Texas/TransTexas Gas Corp. | | TX | In service 1996 | |
| Midcontinent Express Pipeline | Midcontinent Express Pipeline LLC | AL, LA, MS, OK, TX | In service 2009 | |
| Midcontinent Express Pipeline | Midcontinent Express Pipeline LLC (Kinder Morgan / Energy Transfer JV) | OK, TX, LA, MS, AL | 2008–2009 | |
| Midcontinent Express Pipeline Expansion | Midcontinent Express Pipeline LLC | LA, MS, TX | In service 2010 | |
| Midcontinent Supply Header Interstate Pipeline Project | Cheniere Midstream Holdings, Inc. | OK | In service 2020 | |
| Middlebourne III Compressor Station | Antero Midstream LLC | WV | | |
| Middlebourne IV Pipelines | Antero Midstream LLC | WV | | |
| Middlesex Expansion Project | Texas Eastern Transmission, LP/Middlesex Extension Project | NJ | In service 2021 | |
| Midland Deliverability Enhancement Project | Texas Gas Transmission, LLC | KY | | |
| Midland-to-Sealy Pipeline | Enterprise Products Partners | TX | In service 2018 | |
| Midscale Trains 1-9 Project | Corpus Christi Liquefaction, LLC | | | |
| Midship Pipeline | Cheniere | OK | In service 2020 | |
| Midwestern Gas Transmission CP20-57 | Midwestern Gas Transmission Company | KY | | |