Furthest away signage on either a BGS or mileage sign for cities

[DTComposer]

I am pretty sure Portland was listed on a mileage sign on I-5 just north of Stockton, which would be about 620 miles, but I haven't driven that stretch in a while.

Found the Portland sign (628 miles) on I-5 just north of CA-12:

https://maps.app.goo.gl/pnahKDUBxZZkCQ5s7

[Rothman]

Doing the math, 781 miles would put it somewhere around the I-84 junction.  But I don't see any GSV history of any mileage sign around there listing San Francisco.

Heh.  We're talking early 1980s for when I first saw it, so it sorta predates GSV.

[JayhawkCO]

Yeah, looks like farthest in Utah is 511 miles for Reno.