|No. of teams||8|
|Sugar Land Skeeters (2018)|
|Most titles||Somerset Patriots (6)|
The Atlantic League of Professional Baseball is a professional, independent baseball league located primarily in the Mid-Atlantic and Northeastern United States, especially the greater metropolitan areas of the Northeast megalopolis, with one team located in Texas. League offices are located in Lancaster, Pennsylvania.
The Atlantic League operates in cities not served by Major or Minor League Baseball teams and is not affiliated with either; most of its teams are within suburbs and exurbs too close to other teams in the organized baseball system to have minor league franchises of their own. The Atlantic League requires cities to have the market for a 4,000 to 7,500-seat ballpark and for the facility to be maintained at or above AAA standards.  When Atlantic League professionals are signed by MLB clubs, they usually start in their Double-A or Triple-A affiliates.  The league uses a pitch clock of 12 seconds and a maximum time between innings of two minutes, five seconds in an effort to speed up the game. 
In 1998, the Atlantic League of Professional Baseball played its inaugural season, with teams in Bridgewater, Newark, and Atlantic City, New Jersey; Nashua, New Hampshire; Newburgh, New York; and Bridgeport, Connecticut. The creation of the league was the result of the New York Mets' objection to Frank Boulton's proposal to move the former Albany-Colonie Yankees because of its territorial rights to the region. Boulton, a Long Island native, decided to create a new league that would have a higher salary cap for its players and a longer season than most of the other independent baseball organizations. He modeled the Atlantic League after the older Pacific Coast League, with facilities that exceed AAA-level standards. Boulton also emphasized signing players of Major League Baseball experience for all Atlantic League teams, raising the level of play above other independent leagues.
In 2010, the league announced that it would be expanding to Sugar Land, Texas and adding its first franchise not located in an Atlantic coast state.  The Sugar Land Skeeters began play in 2012. In 2010, amid financial struggles, the Newark Bears moved from the Atlantic League to the Can-Am League, leaving the Bridgeport Bluefish and Somerset Patriots as the only teams remaining from the league's inaugural season.  In the summer of 2013, then-ALPB President Frank Boulton announced that he would be resigning so that he could devote more time to operating the Long Island Ducks. He was replaced by longtime high-ranking Major League Baseball executive Rick White.  On July 8, 2015, the Atlantic League began using Rawlings baseballs with red and blue seams, virtually unused in the sport since the American League swapped the blue in their seams for red in 1934. 
On September 1, 2015, the Atlantic League announced conditional approval for an expansion team or a relocated team to play in New Britain, Connecticut for the 2016 season.     On October 21, 2015, the Camden Riversharks announced they would cease operations immediately due to the inability to reach an agreement on lease terms with the owner of Campbell's Field, the Camden County Improvement Authority.  The team was replaced by the New Britain Bees for the 2016 season.  On May 29, 2016, Jennie Finch was the guest manager for the league's Bridgeport Bluefish, thus becoming the first woman to manage a professional baseball team. 
Shortly before the conclusion of the 2017 season, the city of Bridgeport, Connecticut voted to not continue with professional baseball in the city and announced plans to convert The Ballpark at Harbor Yard into a music amphitheater; the Bridgeport Bluefish announced plans to relocate to High Point, North Carolina in 2019 when the construction of a new multipurpose facility in High Point is completed.  League officials announced the return of the Pennsylvania Road Warriors, an all road game team, to keep the league at an even eight teams while the Bluefish go inactive for the 2018 season. 
The Atlantic League is generally regarded as the most successful and highest level of baseball among independent leagues.   Two former Atlantic League players have been inducted into the Baseball Hall of Fame: Tim Raines and Rickey Henderson. Other notable former and future Major League ballplayers who have played in the league include Roger Clemens, Scott Kazmir, Dontrelle Willis, Juan González, John Rocker and José Canseco, and several others have coached or managed, including Gary Carter, Tommy John, Bud Harrelson, Gary Gaetti and Sparky Lyle. The Atlantic League has consistently posted higher per game and per season attendance numbers than other independent circuits including the American Association, Can-Am League, and Frontier League.    
In 2015, the Atlantic League experienced a watershed moment for independent baseball when it signed a formal agreement with Major League Baseball which put into writing the rules which the ALPB would follow in selling its players' contracts to MLB clubs and their affiliates. This marked the first time that MLB, which has enjoyed a U.S. Supreme Court-granted antitrust exemption since 1922, had made any formal agreement with or acknowledgment of an independent baseball league. 
|Lancaster Barnstormers||2005||Lancaster, Pennsylvania||Clipper Magazine Stadium||6,000|
|Southern Maryland Blue Crabs||2008||Waldorf, Maryland||Regency Furniture Stadium||4,200|
|Sugar Land Skeeters||2012||Sugar Land, Texas||Constellation Field||7,500|
|York Revolution||2007||York, Pennsylvania||PeoplesBank Park||5,200|
|High Point Rockers||2019 ||High Point, North Carolina||BB&T Point  ||5,000|
|Long Island Ducks||2000||Central Islip, New York||Bethpage Ballpark||6,002|
|New Britain Bees||2016||New Britain, Connecticut||New Britain Stadium||6,146|
|Somerset Patriots||1998||Bridgewater, New Jersey||TD Bank Ballpark||6,100|
League members Moved to another league
- "Atlantic League Market Requirements". Atlantic League of Professional Baseball. Archived from the original on May 2, 2006. Retrieved May 6, 2006.
- Walk, John (May 18, 2012). "Ian Thomas earns first affiliated contract". The York Dispatch.
- Beach, Jerry (July 13, 2018). "For the Atlantic League, the All-Star Game is All About Its Amazing Balancing Act". Forbes. Retrieved September 1, 2018.
- Reichard, Kevin (May 17, 2010). "Atlantic League to expand to Sugar Land". Ballpark Digest. Retrieved July 11, 2015.
- Reichard, Kevin (October 6, 2010). "It's official: Bears to Can-Am Association". Ballpark Digest. Retrieved July 11, 2015.
- Merrill, Everett (February 5, 2014). "Atlantic League's New President Wants To Innovate". Baseball America. TEN: The Enthusiast Network. Retrieved July 11, 2015.
- Fagan, Ryan (June 30, 2015). "Atlantic League set to introduce red, white and blue baseballs". Sporting News. Retrieved July 11, 2015.
- "New Britain gains Atlantic League OK". Record-Journal. September 1, 2015.
- "Baseball Will Likely Return to New Britain Next Season". NBC Connecticut. September 1, 2015.
- "Conditional Deal For Baseball In New Britain In 2016". CBS Connecticut. September 1, 2015.
- "New Britain Conditionally Approved to Begin Atlantic League Play in 2016". Atlantic League Professional Baseball: Newswire. September 1, 2015.
- "Riversharks Baseball Ceases Operation; Team Not Offered New Lease". Atlantic League Professional Baseball: Newswire. October 22, 2015.
- Stacom, Don (October 22, 2015). "Atlantic League Baseball: Camden Is Out, New Britain Is In". Hartford Courant. Retrieved October 23, 2015.
- Eisenberg, Matt (May 29, 2016). "Guest manager Jennie Finch leads Bridgeport Bluefish to win". Espn.go.com. Retrieved May 31, 2016.
- "End Of An Era: Bluefish Will Be Moving From Bridgeport To North Carolina". Daily Voice. Bridgeport, Connecticut. September 10, 2017. Retrieved December 27, 2017.
- "2018 Atlantic League Schedule Announced". atlanticleague.com. October 23, 2017. Retrieved December 27, 2017.
- Fehrman, Craig (May 9, 2012). "Down And Out In Baseball's Indie Leagues; Or, What Made Tommy John Want To Rake The Infield?". Deadspin. Gawker Media. Retrieved July 11, 2015.
- "Creation of developmental indy league announced". Ballgamers. June 28, 2013. Retrieved July 11, 2015.
- Knight, Graham. "Independent Leagues 2014 Attendance". BaseballPilgrimages.com. Retrieved July 11, 2015.
- Recihard, Kevin (September 16, 2013). "2013 Independent Attendance by League". Ballpark Digest. Retrieved July 11, 2015.
- Reichard, Kevin (September 24, 2012). "2012 Independent Attendance by League". Ballpark Digest. Retrieved July 11, 2015.
- Reichard, Kevin (September 19, 2011). "2011 Independent Average Attendance by League". Ballpark Digest. Retrieved July 11, 2015.
- Cooper, J.J. (May 15, 2015). "MLB, Atlantic League Sign Player Transfer Agreement". Baseball America. TEN: The Enthusiast Network. Retrieved July 11, 2015.
- Reichard, Kevin (March 12, 2018). "Independent High Point Team Officially on Tap for 2019". Ballpark Digest.
- Spedden, Zach (April 12, 2018). "New for 2019: BB&T Point". Ballpark Digest. Retrieved April 17, 2018.
- Rose, Alex (April 11, 2018). "City leaders break ground for High Point stadium project; stadium to be named 'BB&T Point'". WGHP. Archived from the original on April 17, 2018. Retrieved April 17, 2018.
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