Founded 70 years ago in 1955 as a charter member of the Northwest League, the Emeralds were named in a contest, won in January by 11-year-old Bowen Blair.

[7] The Emeralds played in northwest Eugene in 4,000-seat Bethel Park, at Roosevelt Boulevard and Maple Street (44°03′52″N 123°08′43″W / 44.0644°N 123.1454°W / 44.0644; -123.1454),[8] later torn down for the construction of a highway that wasn't built.

The second pick in the 1966 MLB draft, future hall of famer Reggie Jackson played his first professional games at Bethel Park, as a 20-year-old center fielder, following his sophomore season at Arizona State.

[16][17] 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.

Civic Stadium also hosted semi-pro baseball teams, sponsored by local timber companies, until Bethel Park was built in 1950.

[23] In 2009, playing for the Emeralds, Nate Freiman led the league for the season in RBIs (68), extra-base hits (33) and total bases (140).

[26] Following the 2014 season, the Emeralds switched from being an affiliate of the San Diego Padres to the Chicago Cubs, who signed Eugene to a two-year deal through 2016.

The awards were due to their work with Children's Miracle Network and their honorary player that year, Hayden Kumle.

In the winter of 2020 as part the reorganization of minor league baseball, Eugene received an invitation to play as the High-A affiliate of San Francisco Giants.

[37] On March 13, 2024, the Eugene City Council voted to place a $15 million bond measure on the ballot for their May 21 primary election.