There has been a lot of talk about the extension of the 710 into Pasadena lately. The idea of connecting the San Gabriel Valley with the Antelope Valley in a direct route has been thought about since at least the 1920's.
Various proposals have been floated, one of which was to build a tunnel under the San Gabriels and extend Los Angeles Freeways to the north, opening up the Antelope Valley to urban sprawl just as happened in the San Fernando and San Gabriel Valley.
We are lucky in Pasadena and Altadena that the San Gabriel Mountains form such an impenetrable barrier. If it was more practical, Lake, Fair Oaks and/or Lincoln Avenues would have become multi-lane highways into the new Los Angeles suburb of Antelope Valley.
Fortunately, for the moment at least, our neighborhoods are spared the problems of being the feeder system through Pasadena and Altadena to another sprawling suburban valley. Thank goodness for the San Gabriel Mountains and the dead ends at the top of Lake, Fair Oaks and Lincoln Avenues!!!
This rendering was found recently at a local fleamarket and shows what was being proposed back in the early 1950's when the expansion of suburbia was on the mind of Los Angeles.....