Various steel treks- 800,820,830,850 920,930 950 970 990- 26" "Mountain bikes" are really great urban,suburban light trail, grass, gravel roads
do ANYTHING bikes with 26" wheels/tires-so you can get any width from about 1"(25mm) to 2.4"-(60mm)
In NOLA- they go for $50-$225(900 series are DB CRMO steel)-

Or the Trek 700,720,730,750 MORE OR LESS the same as the above but with 700c wheels tires-you can usually get a 40mm tire on them-so great for potholed streets

On the 700 and 800 some are SEAT TUBE only Chrome MOLY STEEL with the rest of the frame being cheaper high tensile steel-
Functionally it hardly matters-but they are worth less(it was a Trek cheap out-they could badge them (CHROME MOLY STEEL seat tube)-all you saw was CRMO-
They all are decent bikes- 21 speeds-decent components-rugged potholed street worthy but certainly good for light trail work

Other manufacturers made the same sort of bikes-Specialized hard rock-and Diamond back
And Schwinn made some "Paramount" mountain bikes-all cromo steel-some with the splatter paint paint-nice bikes-
obviously not the same bikes as the Paramount road bikes the Vintage Nuts drool over-much cheaper-$75-$200 nice bikes

If possible avoid the bikes of this vintage with suspension folks-later ones frequently had cheapo suspension forks-they worked just fine-but the suspension forks are rarely needed with big high volume low pressure tires

The above bikes early 1990's thru about 2000 usually didn't have suspension folks-nothing wrong with them-but they are cheap heavy forks-not needed-"
But if you get a good deal on one-don't let it discourage you from buying
And many folks here will claim a 900 series isn't worth $100-BS they are full crmo double butted steel frames decent shimano components
A new bike-same same-would cost at least $600 similarly equipped-
and POS single speeds-$300 or more for DB chrome moly steel frame(assuming folks in hilly San Fran have avoided those poseur single bikes and the fixed gear death machines)

Luck
charlie
PS Yes I am just kidding the single speed fixed gear crowd-I can never resist a cheap shot!!
And aluminum frames great too-but the steel is more dent resistant-thinner tubing slightly more aesthetic-perhaps you don't have to be as careful when you mount a kickstand on steel-but you can certainly mount kickstands on aluminum frames-get a bike with a kickstand if possible-the greenfield ones cost $10 or so to buy-and a bike without a kickstand is a pain-until you put a kickstand on it
GOOD LOCK

PPS Fietsbob is right-those treks have Specialized and Diamondback cousins-
now some of the 920 930 950 ARE ACTUAL made in usa with made in USA tubing True Temper-