# USL Pro, USL and Championship: history sources

Research checked September 11, 2026. Executable data: `lib/data/usl-championship-history.ts`. This component covers the men's professional competition launched as USL Pro in 2011, renamed USL for 2015 and USL Championship for 2019. Earlier USL First/Second Division and NASL seasons are not silently treated as Championship seasons. League One, League Two and announced future entrants have separate source files.

## Snapshot rules

An active season means the club actually participated in that competition. Announcements and franchise purchases do not create earlier playing seasons. The 2026 snapshot describes current participation, not a completed season. MLS-operated reserve clubs are included during their USL seasons. Occasional 2013/2014 interleague games against MLS Reserve League opponents do not make those opponents USL members.

The initial 2011 map includes **15 participating clubs**: the twelve that finished plus Puerto Rico United, River Plate Puerto Rico and Sevilla FC Puerto Rico. The latter three were removed in May after playing league games. USL's [May 12, 2011 schedule revision release](https://www.oursportscentral.com/services/releases/usl-pro-schedule-revisions-announced/n-4202060), preserved by OurSports Central and identified there as a league news release, confirms their games continued to count. Therefore this participation count differs intentionally from the twelve-team retrospective on the [league's About page](https://uslchampionship.sportngin.com/about).

Geographic inputs are manually chosen, rounded reference points in the named home municipality or community. They are approximations for comparing distances, not surveyed stadium positions, driving routes, fan allegiances or market boundaries. A season uses the regular home municipality at its end when a permanent move occurred during that year. Individual alternate fixtures and pandemic-only venue substitutions are excluded. New York City borough venues share the New York municipal reference point. Phoenix Rising's two tribal-community eras use representative points near their host districts rather than the centroid of the much larger reservation. Antigua's 2013 traveling season retains its St. John's base; it does not imply home matches took place there that year. Canadian, Antiguan and Puerto Rican participants remain eligible even though the county layer covers the fifty states and D.C.

Colors are editorial, legible variations on club palettes. Logo eras cover major identity changes; anniversary marks, championship stars and every small badge revision are outside this edition. A crest's source must be recorded separately; an unavailable historical mark should be labeled as unavailable rather than invented. Clubs receiving another club's operating rights are represented by their own public identity, not asserted to share sporting records. This matters for Phoenix FC versus Arizona United, Fresno versus Monterey Bay, Ottawa versus Miami and Orlando versus Louisville.

## Annual membership checks

| Season | Participating clubs | Evidence |
| --- | ---: | --- |
| 2011 | 15 | [League schedule revision](https://www.oursportscentral.com/services/releases/usl-pro-schedule-revisions-announced/n-4202060); [2011 season table](https://en.wikipedia.org/wiki/2011_USL_Pro_season) for the initial fifteen and removed teams |
| 2012 | 11 | [USL's 2013 media guide](https://nyc3.digitaloceanspaces.com/sportsarchive-documents/prod/60e89c859d584/2013%20USL%20PRO%20Media%20Guide_Web.pdf), prior-season records; [2012 season table](https://en.wikipedia.org/wiki/2012_USL_Pro_season) |
| 2013 | 13 | [2013 USL Pro media guide](https://nyc3.digitaloceanspaces.com/sportsarchive-documents/prod/60e89c859d584/2013%20USL%20PRO%20Media%20Guide_Web.pdf); [league retrospective](https://www.uslchampionship.com/news_article/show/1317147) |
| 2014 | 14 | [Dayton's 2014 schedule release](https://www.oursportscentral.com/services/releases/dayton-dutch-lions-fc-pro-schedule-announced/n-4734301), preserved club release; [U.S. Open Cup announcement](https://www.mlssoccer.com/news/us-open-cup-details-2014-edition-released-weekend-games-largest-field-modern-era) lists Arizona United after Phoenix FC's preseason replacement |
| 2015 | 24 | [Seattle's official inaugural schedule release](https://www.soundersfc.com/news/usl-pro-unveils-inaugural-sounders-fc-2-schedule) |
| 2016 | 29 | [League regular-season attendance report](https://www.uslchampionship.com/news_article/show/703007-usl-total-attendance-soars-by-33-percent-in-2016) |
| 2017 | 30 | [Official conference alignment](https://www.uslchampionship.com/news_article/show/742742-usl-announces-2017-conference-alignment) |
| 2018 | 33 | [Official conference alignment](https://www.uslchampionship.com/news_article/show/875057-usl-reveals-2018-conference-alignment) |
| 2019 | 36 | [Official conference alignment](https://www.uslchampionship.com/news_article/show/977011-usl-championship-unveils-2019-conference-alignment) |
| 2020 | 35 | [Official schedule](https://www.uslchampionship.com/news_article/show/1076583-usl-championship-unveils-2020-schedule); [July restart report](https://www.uslchampionship.com/news_article/show/1115277) confirms all thirty-five returned |
| 2021 | 31 | [Official four-division alignment](https://www.uslchampionship.com/news_article/show/1149641-usl-championship-unveils-2021-league-alignment) |
| 2022 | 27 | [Official competition format](https://www.uslchampionship.com/news_article/show/1199893) |
| 2023 | 24 | [Official preseason club overview](https://www.uslchampionship.com/news_article/show/1258230) |
| 2024 | 24 | [League's full matchday report](https://www.uslchampionship.com/news_article/show/1307583) |
| 2025 | 24 | [U.S. Soccer's Open Cup field](https://www.ussoccer.com/stories/2025/01/format-and-96-team-field-finalized-for-2025-lamar-hunt-us-open-cup), all twenty-four Championship clubs |
| 2026 | 25 | [Official competition format and complete alignment](https://www.uslchampionship.com/news_article/show/1351433) |

The [Championship historical timeline and former-club table](https://en.wikipedia.org/wiki/USL_Championship) were used as a secondary cross-check for the complete roster of former participants. Its founding years are not substituted for first playing seasons: Fresno first played in 2018, Saint Louis in 2015, and Cincinnati in 2016. The dataset has 65 club records. Active ranges can be disjoint; North Carolina is present in 2018–2020 and 2024–2025, while its League One seasons are in the other dataset.

## Names, moves and transitions

| Decision represented | Supporting source |
| --- | --- |
| LA Blues in Fullerton; OC Blues in Irvine from 2014; Orange County SC from the 2017 playing season | [2013 official media guide](https://nyc3.digitaloceanspaces.com/sportsarchive-documents/prod/60e89c859d584/2013%20USL%20PRO%20Media%20Guide_Web.pdf), club directory; [OCSC's Irvine history](https://www.orangecountysoccer.com/news/2023/03/10/rooted-in-orange-county-celebrating-ten-years-of-ocsc-in-irvine/); [January 2017 club release](https://www.orangecountysoccer.com/news/2017/01/12/orange-county-gets-their-man-logan-pause-named-blues-head-coach/) still describes the forthcoming rebrand |
| Charleston's new crest and Mount Pleasant home from 2020 | [Battery's official club history](https://www.charlestonbattery.com/club/) |
| Pittsburgh's city crest and black/gold identity from 2018 | [League's club history feature](https://www.uslchampionship.com/news_article/show/1363728); early venue directory in the [2013 media guide](https://nyc3.digitaloceanspaces.com/sportsarchive-documents/prod/60e89c859d584/2013%20USL%20PRO%20Media%20Guide_Web.pdf) |
| Dayton's earlier Bellbrook and Beavercreek homes; DOC Stadium in West Carrollton during 2014 | [Official DOC Stadium history](https://dutchlionsfc.com/docstadium/); [club history](https://dutchlionsfc.com/history/); [historical stadium list](https://en.wikipedia.org/wiki/Dayton_Dutch_Lions) |
| VSI Tampa Bay based in Plant City; LA Blues in Fullerton; Phoenix FC in Tempe | Club directories in the [2013 USL Pro media guide](https://nyc3.digitaloceanspaces.com/sportsarchive-documents/prod/60e89c859d584/2013%20USL%20PRO%20Media%20Guide_Web.pdf) |
| Puerto Rico reference municipalities Aguada, Carolina and Juncos | [Puerto Rico United stadium history](https://en.wikipedia.org/wiki/Puerto_Rico_United), [River Plate's temporary Carolina venue](https://en.wikipedia.org/wiki/Club_Atl%C3%A9tico_River_Plate_Puerto_Rico), [Sevilla's Juncos history](https://en.wikipedia.org/wiki/Sevilla_FC_Puerto_Rico). These are secondary sources because surviving primary club pages are incomplete; Carolina is used for River Plate's actual 2011 home rather than its planned Fajardo stadium. |
| Orlando's first team plays its last USL season at Disney in 2014, then joins MLS in 2015 | [2014 season record](https://en.wikipedia.org/wiki/2014_USL_Pro_season); [Orlando's official history in its OCB venue announcement](https://www.orlandocitysc.com/news/orlando-city-b-play-2017-usl-season-new-downtown-soccer-stadium) |
| Orlando City B is separate, Melbourne in 2016 and Orlando in 2017 | [Official 2017 venue announcement](https://www.orlandocitysc.com/news/orlando-city-b-play-2017-usl-season-new-downtown-soccer-stadium) |
| Charlotte Independence moves to Matthews during 2017 | [Club's move announcement](https://www.charlotteindependence.com/news/2017/02/01/independence-moving-to-matthews/) |
| Seattle Sounders 2 move from Tukwila to Tacoma in 2018, rename Tacoma Defiance for 2019 | [Sounders' rebrand report](https://www.soundersfc.com/tacoma-defiance/news/tacoma-defiance-rebrand-completes-seattle-sounders-player-development-restructur) |
| Swope Park move to Kansas City, Kansas during 2018; become Sporting KC II in 2020 | [Venue announcement](https://www.sportingkc.com/news/rangers-play-usl-home-matches-children-s-mercy-park-remainder-2018-season), [name announcement](https://www.sportingkc.com/news/sporting-club-s-usl-championship-team-become-sporting-kansas-city-ii) |
| Bethlehem Steel play in Chester in 2019, before becoming Philadelphia Union II in 2020 | [Official March 2019 match report](https://www.philadelphiaunion.com/unionii/news/match-recap-bethlehem-steel-fc-2-pittsburgh-riverhounds-sc-2-29785); [2020 Championship schedule](https://www.uslchampionship.com/news_article/show/1076583-usl-championship-unveils-2020-schedule) |
| Toronto FC II move from Vaughan to Toronto for 2018 | [Official 2018 season preview](https://www.torontofc.ca/news/toronto-fc-ii-2018-season-preview) |
| Real Monarchs move from Sandy to Herriman during 2018 | [Official March 2018 venue update](https://www.rsl.com/news/real-monarchs-slc-move-home-opener-rio-tinto-stadium), [May 2018 confirmation of the move](https://www.rsl.com/news/real-monarchs-slc-host-sacramento-republic) |
| Atlanta United 2 use Lawrenceville in 2018, Kennesaw from 2019 | [Official venue announcement](https://www.atlutd.com/news/atlanta-united-2-play-2019-home-matches-fifth-third-bank-stadium) |
| Portland Timbers 2 use Hillsboro in 2020 | [Official partnership and venue announcement](https://www.timbers.com/t2/news/portland-timbers-and-hillsboro-hops-announce-new-t2-partnership) |
| Tulsa Roughnecks become FC Tulsa in 2020 | [Official name, color and crest announcement](https://www.uslchampionship.com/news_article/show/1069155) |
| Louisville retains its original crest through 2020 and uses the new shield in 2021 | [January 2020 reversal of the earlier proposal](https://www.uslchampionship.com/news_article/show/1076061); [November 2020 final crest announcement](https://www.uslchampionship.com/news_article/show/1133228) |
| Arizona United becomes Phoenix Rising in 2017; Phoenix moves to Wild Horse Pass in 2021 and Phoenix proper in 2023 | [2017 alignment](https://www.uslchampionship.com/news_article/show/742742-usl-announces-2017-conference-alignment); [official Wild Horse Pass move](https://www.phxrisingfc.com/news/phoenix-rising-fc-moves-stadium-and-professional-training-center-to-wild-horse-pass/); [2023 site approval](https://www.phxrisingfc.com/news/phoenix-city-council-unanimously-approves-lease-for-phoenix-rising-fc-to-relocate-its-stadium-to-38th-street-and-washington/) |
| North Carolina's disjoint Championship spells | [Official 2024 return announcement](https://www.uslchampionship.com/news_article/show/1280956); absent from the [2026 alignment](https://www.uslchampionship.com/news_article/show/1351433) |
| Oakland's 2023–2024 Hayward home | [League's archived 2024 club page](https://www.uslchampionship.com/oakland-roots-sc-roster-2024) |
| Brooklyn's men's debut is 2026 | [2026 alignment](https://www.uslchampionship.com/news_article/show/1351433) supersedes the [original planned 2025 debut](https://www.uslchampionship.com/news_article/show/1303990) |

The current venue municipalities (including Detroit City in Hamtramck, Monterey Bay in Seaside, Tampa Bay in St. Petersburg, Loudoun in Leesburg and Miami FC in University Park) were checked against the league's club directory, current club venue information and the [current/former club location table](https://en.wikipedia.org/wiki/USL_Championship). The plotted geographic coordinates themselves are editorial cartographic inputs, not numbers quoted from those sources.

## Crest provenance

The companion [historical crest registry](usl-championship-logo-sources.json) records the exact artwork URL, source page and verification date for every downloaded historical mark. The [additional departed-club registry](usl-extra-logo-sources.json) supplies Austin Bold and the departed League One clubs. Images are only resized or converted to PNG; source artwork and any opaque background are preserved.

Major crest revisions are represented separately, including [Harrisburg's 2014 update](https://www.sportslogos.net/logos/list_by_team/3801/Harrisburg-City-Islanders-Logos/), [Los Angeles Blues in 2012](https://www.sportslogos.net/logos/list_by_team/3802/Los-Angeles-Blues-Logos/), [Orange County Blues in 2015](https://www.sportslogos.net/logos/list_by_team/5221/Orange-County-Blues-FC-Logos/), [Rochester in 2016](https://www.sportslogos.net/logos/list_by_team/3806/Rochester-Rhinos-Logos/), and [Wilmington in 2014](https://www.sportslogos.net/logos/list_by_team/3807/Wilmington-Hammerheads-FC-Logos/). These artwork-catalog dates are secondary evidence, not substitutes for the league and club sources supporting membership.

Richmond uses its original ball-and-text crest in 2011 and the red K shield from 2012 through its remaining Championship seasons. The [2012 unveiling report](https://www.soccerwire.com/news/richmond-kickers-unveil-new-logo/) includes contemporaneous club comments and confirms immediate use for the 2012 professional team. The original mark is preserved in [Wikimedia's historical gallery](https://fr.wikipedia.org/wiki/Kickers_de_Richmond); the 2012–2024 artwork is [documented separately on Commons](https://commons.wikimedia.org/wiki/File:Richmond_Kickers_Logo_2012_to_2024.svg). The SportsLogos USL page labels a newer Richmond shield as 2011, so that label was rejected. Likewise, Revolution II's 2020–2021 flag-and-II artwork comes from the league's [actual 2020 standings](https://www.uslleagueone.com/standings-2020), avoiding the newer mark in a Wikimedia file misleadingly named 2021.

## Reproducibility

For each integer season from 2011 through 2026, filter `activeSeasons`, select the unique era covering that year, and let its optional municipality/coordinates override the club default. Check the resulting length against `USL_CHAMPIONSHIP_SEASON_COUNTS`. A season outside this range belongs to the separate planned-future dataset; extending an active range would incorrectly imply confirmed future competition membership.