Control Cities in California

[mrsman]

The Riverside Fwy portion (east of I-5)  is older than the Artesia/Gardena/Redondo Beach Fwy portions.  When the 91 terminated at I-5, it made sense that L.A. was the control.

Hmmmmm, so that explains why before the 5/91 interchange was rebuilt in the 90s, WB 91 to NB 5 was a left exit.

I believe so.  At many Ys, they were designed with left exits and entrances as a cost-saving measure.  Cheaper than makig a full-fledged flyover.  There were a lot of left entrances along the entire 101 freeway, including the old Santa Ana Fwy.  The Long Beach fwy and Firestone exits are also on the left.

[Occidental Tourist]

The WB 91 to NB 5 was a left exit because the 91 originally terminated as a merge into the right-hand lanes of the 5 north, not as a cost-saving measure. When the Artesia Freeway portion of the 91 was built, they built the mainline lanes for continuing onto the 91 as a new bridge to the right of and crossing over the preexisting lanes merging down to the 5.

Prior to the Artesia Freeway being built, the SB 5 did use a left exit to the EB Riverside Freeway portion of the 91.  This was sort of a cost-saving measure insomuch as the 5 had the Union Pacific tracks to its immediate south (still does) and so there wasn't much right of way for a right-side transition ramp and flyover.

[TheStranger]

The Riverside Fwy portion (east of I-5)  is older than the Artesia/Gardena/Redondo Beach Fwy portions.  When the 91 terminated at I-5, it made sense that L.A. was the control.

Hmmmmm, so that explains why before the 5/91 interchange was rebuilt in the 90s, WB 91 to NB 5 was a left exit.

I believe so.  At many Ys, they were designed with left exits and entrances as a cost-saving measure.  Cheaper than makig a full-fledged flyover.  There were a lot of left entrances along the entire 101 freeway, including the old Santa Ana Fwy.  The Long Beach fwy and Firestone exits are also on the left.

IIRC wasn't the Long Beach Freeway left exit from the Santa Ana Freeway primarily also to maximize limited right of way?

The (now removed) exit from I-5 north to Route 42 (Firestone) west I think was a vestige, to some extent, of when Firestone Boulevard west of there and the Manchester Avenue segment east of there (now the Santa Ana Freeway frontage road) was all part of 1934-1950s Route 10.