The Pioneer League began in 1939 with six teams in
Idaho and
Utah, operating at the
Class C level. The original six teams were the
Boise Pilots,
Lewiston Indians,
Ogden Reds,
Pocatello Cardinals,
Salt Lake City Bees, and
Twin Falls Cowboys. With players in short supply due to
World War II, the league suspended operations for the 1943 through 1945 seasons. In 1948, the league expanded by adding two teams in
Montana; the
Billings Mustangs and
Great Falls Electrics. In these early years, teams in the league either operated independently or were affiliated with
Major League Baseball (MLB) or
Pacific Coast League (PCL) parent clubs, as the PCL was attempting to grow into a third major league (a bid that ultimately failed). When MLB's
Los Angeles Dodgers displaced the PCL's
Hollywood Stars in 1958, the Stars relocated and became the "new" Salt Lake City Bees, remaining in the PCL and taking away the Pioneer League's largest market. By 1959, the Pioneer League was down to six teams; Billings and Great Falls along with the
Boise Braves,
Idaho Falls Russets,
Missoula Timberjacks, and
Pocatello Athletics. The league operated at the
Class A level for one year (1963), before changing to Rookie league in 1964, when there were only four teams in the league; the
Idaho Falls Angels,
Magic Valley Cowboys,
Pocatello Chiefs, and
Treasure Valley Cubs. By 1978, the league had again grown to eight teams — Billings and Idaho Falls along with the
Butte Copper Kings,
Calgary Cardinals,
Great Falls Giants,
Helena Phillies,
Lethbridge Dodgers, and
Medicine Hat Blue Jays. With the exception of 1986 (when there were six teams), there have been at least eight teams in the league since then. In 2016, total league attendance was 616,686, down slightly from the 2015 total of 633,622. In its final years as an MLB-affiliated league, the Pioneer League was one of two "Rookie Advanced" minor leagues along with the
Appalachian League. As such, it occupied the second-lowest rung in the minor league ladder. Although classified as a Rookie league, the level of play was slightly higher than that of the two "complex" Rookie leagues, the
Gulf Coast League and
Arizona League. Unlike the complex leagues, Pioneer League teams charged admission and sold concessions. It was almost exclusively the first fully professional league in which many players competed; most of the players had just been signed out of high school. It was a short-season league that competed from late June (when Major League teams signed players whom they selected in the amateur draft) to early September. After the 2018 season, the
Helena Brewers relocated to
Colorado Springs, Colorado, where they became the
Rocky Mountain Vibes. 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 the reorganization of Minor League Baseball in 2021, the Pioneer League was converted to an
independent baseball league and was granted status as an MLB Partner League. The reconfigured league continued with the same franchises using the same identities, with the exception of the
Orem Owlz who relocated to
Windsor, Colorado, as the
Northern Colorado Owlz. The
Boise Hawks also joined the Pioneer League in 2021 after moving from the
Northwest League. The Pioneer League announced a five-year naming rights deal between the league and ticket vendor TicketSmarter that would have the league go as The Pioneer Baseball League presented by TicketSmarter starting in time for the 2022 season. On April 10, 2024,
Kelsie Whitmore signed with the
Oakland Ballers of the Pioneer League. She became the first woman to play for that league later that year. On June 6, 2024, she became the first female player to start a Pioneer League game. In that game she struck out one batter, gave up 6 hits, two earned runs, and a walk. The Ballers would lose the game by one run. On the same road trip, she gave up 11 earned runs in 4 and 2/3rds innings. The league further expanded into California for its 2026 season, adding teams in
Long Beach and
Modesto – the latter as a replacement for the
Modesto Nuts of the
California League, who moved to
San Bernardino and became the
Inland Empire 66ers. Simultaneously, the league's presence in Colorado came to an abrupt end, after both the
Rocky Mountain Vibes and short-lived Colorado Springs Sky Sox folded, and the
Grand Junction Jackalopes relocated. == Teams ==