Chgo/SF: How strong the link?

Here's a topic that hasn't come up here: what is the relationship between Chicago and San Francisco? We seem to get hyper-focused on LA with which Chicago has a spirited rivalry. It no doubt came form the similiarities of population and LA passing up Chicago, as well as being the two non-NYC global cities in the US. Sheer size of the two cities may obscure there is another city in California, much smaller but part of a huge metro area, that shares so much with Chicago. But what about San Francisco? It seems to me we share a lot with the city by the bay. Going back to the time of the first continental railroad, when the Union Pacific and the Central Pacific joined up at Promitory Point, essentially what was happening was the joining of SF (Oak) with Chicago. Both cities were influenced by Daniel Burnham (oblivously more so in Chicago than in SF) and Chicago architetects have played a prominent role in the development of SF architeture, including the Bay and GG bridges. Educationally both areas offer up the likes of Northwestern, Chicago, Cal, and Stanford. ORD/SFO is one of the nation's strongest air links. No other cities away from the northeast corridor project urbanity the way that Chicago and San Francisco do; in that sense, they are in a class by themselves. Downtown, SF may be more like Chicago than any other city: two magnets without the sheer size of Manhattan. NY, Chgo, SF, and Boston, IMHO, have the nations most vibrant downtowns, but Boston (with its proximity to NYC) does break away from the pack as a major center the way SF does. A recent thread on the West Coast board showed pictures of SF development (u.c. and planned) and what you see is almost Chicago-like, in scale and scope. I realize there is a lot of speculation in architectural renderings, but if most of this stuff is built, SF will be giving Chicago a good run for its money in what it can offer downtown...something I don't see in-land downtown LA ever accomplishing. So much are the City-by-the-Bay and the City-by-the-Lake kindred souls, joined by urbanity, density, forging true great cities away from the Atlantic, current forgers of the good life, etc. ? How does Chicago relate to San Francisco?>