The corridor is a fully underground, north-south route along mostly densely populated areas on the western side of the Los Angeles Basin; it would be operated as part of the K Line.

The Los Angeles County Metropolitan Transportation Authority (Metro) is prioritizing the project along with pressure from the West Hollywood residents.

However, during the environmental review, Metro determined that if LRT were selected as the preferred mode, the cost for the entire route would exceed the project budget.

In December 2009, the Metro Board decided on LRT as the preferred mode; as a result, the part of the corridor north of Exposition Boulevard was deferred until funds became available.

[9] In September 2016, in a letter to West Hollywood City Council member Lindsey Horvath, Metro CEO Phil Washington outlined several steps Metro is taking to make the Crenshaw/LAX northern extension "shovel ready" should county voters approve Measure M, a countywide ballot measure adding new transit projects and expediting others previously approved under Measure R.[10] The final design of "Phase One" (the original project line south of Exposition Blvd to LAX) would determine how the Phase Two project could or would connect to Phase One.

[11] Metro also studied "Design Option 6" for Phase One, which would extend the Leimert Park tunnel north to the line's northern terminus at Exposition, with an underground station at Crenshaw/Exposition.

On August 17, 2020, Metro recommended three final alignments for environmental analysis and advanced conceptual engineering.

[13][14] The current three alternatives considered are all south to north routes: The following table shows all potential metro stations and the alternatives for which they apply: The city council approved a resolution in May 2018 to expedite its environmental study to speed up the approval process with Metro.

[18] Local Los Angeles U.S. representative Adam Schiff (now Senator) also voiced his support for acceleration in a letter to then Metro CEO Philip Washington in March 2019.