The Edmonton Metropolitan Transit Commission had inherited the Edmonton Transit System's LRT system in 1999 when the Commission was formed.
The Capital Line was the only line open in 1999, and had expanded as far as Heritage Station in the south and Alberta Hospital in the north.
Starting in 2005, the system truly started to expand with the tandem openings of the Metro and Valley Lines.
The Valley Line was a departure from the Capital and Metro Lines, using 70% low floor vehicles at the time, and it later tranisitioned to a full 100% low floor fleet.
Most the Commission's new lines were focused on the low-floor style trams through the 2000s, as it invited development.
The latest line, the Arts Line, opened in 2019, making it the final rail-based rapid transit line, replacing the BRT that had serviced North Edmonton since 2003. It can interline with the southern portions of the Capital and Metro Lines, making it part of the high floor system.