Founded in 1955 as a charter member of the Northwest League, the Emeralds were named in a contest won by 11-year-old Bowen Blair. They won the inaugural pennant as an independent, and remained in the NWL for 14 seasons through 1968. The Emeralds were the first minor-league team to play in Eugene since the disbanding of the
Eugene Larks, who played at Bethel Park for just two seasons, 1950 and 1951. The Emeralds played in northwest Eugene in 4,000-seat Bethel Park, on the northwest corner of Roosevelt Boulevard and Maple Street (), later razed for the construction of a highway that was never built. In 1950 and 1951, Bethel Park was the home of the Eugene Larks of the
Class D Far West League; its outfield is present-day Lark Park. The Larks' final game on August 29, 1968 drew 897 fans for a one-hitter and a 7-0 Emeralds win. The NWL changed to a short-season league in 1966. The second pick in the
1966 MLB draft, future
hall of famer Reggie Jackson, played his first professional games at Bethel Park, hitting a single and home run in his second game. In the 1969 season, the Emeralds were promoted to
AAA status in the
Pacific Coast League (PCL) as the primary affiliate of the
Philadelphia Phillies. The team returned to the Northwest League five years later when the PCL moved the AAA team to
Sacramento for the 1974 season, while the Phillies moved their AAA farm team to the
Toledo Mud Hens of the
International League. Eugene was an independent co-op team shared by the Phillies and
San Francisco Giants in 1974 and became an affiliate of the
Cincinnati Reds in 1975. Entering Triple-A in 1969, the Emeralds moved from Bethel Park to
Civic Stadium. The 6,800-seat facility was owned by the
Eugene School District and was built in 1938 as a venue for high-school football, which was played there until 1968. Civic Stadium also hosted semipro baseball teams, sponsored by local timber companies, until Bethel Park was built in 1950. Facing an outdated stadium and high maintenance costs, in 2010 the Emeralds moved to
PK Park, the new baseball stadium across town that was built by the
University of Oregon. The park is adjacent to the university's
Autzen Stadium and near the
Willamette River. The team shares the facility with the
Oregon Ducks' collegiate baseball team, whose regular season ends in May. Civic Stadium was destroyed by arson in 2015. A new logo, based upon
Sasquatch, was adopted by the Emeralds in 2012. Following the 2014 season, the Emeralds switched their major-league affiliation from the
San Diego Padres to the
Chicago Cubs, with a two-year deal through 2016. The player-development contract was extended through the 2018 season on June 14, 2016. In 2016, the Emeralds were awarded two "Golden Bobblehead" awards for their promotions with
Children's Miracle Network and their honorary player that year, Hayden Kumle. The Emeralds won the NWL title in 2018 despite finishing in last place with a 31–45 record. The team, dubbed the "Bad News Ems", clinched a wild-card playoff spot with a 17-21 record in the second half, second behind
Hillsboro, who had finished first in both halves, and swept Hillsboro and
Spokane in the postseason. The team's .408 regular-season winning percentage was the worst ever for a NWL champion. Following that season, the Emeralds were awarded the 53rd annual Larry MacPhail Award in recognition for their promotions. In 2019, the Emeralds unveiled their Monarcas de Eugene on-field identity as part of minor-league baseball's Copa de Diversion initiative. After the 2020 season was canceled during the
COVID-19 pandemic, Eugene was invited to become the
High-A affiliate of the San Francisco Giants. The Emeralds were assigned to the
High-A West league with five other teams previously of the Northwest League. Eugene ended the 2021 season in first place with a 69–50 record. They then defeated the
Spokane Indians, 3–1, to win the High-A West championship. In 2022, the High-A West was renamed as the Northwest League. The Emeralds began to seek a new stadium following the promotion to the High-A level and its longer season. Team officials met with Lane County officials to discuss the feasibility of constructing a new stadium at the Lane Events Center. On March 13, 2024, the Eugene City Council voted to place a $15 million bond measure on the ballot for the May 21 primary election. This would partially fund the stadium project's expected cost of more than $104 million. However, Lane County administrators had advised a reset in planning before committing to this project. City councilors had previously required this commitment and financial reports of the stadium's operations. The Lane Events Center master plan did not include the Emeralds' stadium because it was too large, requiring removal of the multiuse indoor arena, and would detract from fairground operations by hindering profitable events, with an expected annual loss of $200,000. ==Playoffs==