Pioneer League (Baseball league)

"The Pioneer League is an independent baseball league that operates in the Rocky Mountain region of the United States. From 1939 to 2020, the Pioneer League was affiliated with Minor League Baseball and its teams were affiliated with MLB teams. It operated as a Class C league from 1939 to 1942 and from 1946 to 1962. It was elevated to Class A for 1963 and was a Rookie-level league from 1964 to 2020. As the start of the 2020 season was postponed due to the COVID-19 pandemic before being cancelled on June 30, making the 2019 season the league's last as an MLB-affiliated league of Minor League Baseball. In conjunction with a contraction of Minor League Baseball in 2021, the Pioneer League was converted to an independent baseball league and granted status as an MLB Partner League." -- Wikipedia