While looking at a few old photos of Detroit (might have been new photos of old Detroit), I noticed that there are still a lot of old streetlamps still in existence in the older sections of the city:
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fatdetroit.net%2Fforum%2Fmessages%2F5%2F177338.jpg&hash=8fe015fdfb8149943ba257be39363a8e375d5b58)
These ornate ones are easily from the 40's -- possibly older.
What is/are the oldest street light(s) in your neck of the woods? The actual bulbs or light housings may have been changed or upgraded over the years, but the basic light poles have to be originals.
Go!
There are at least still two ancient ones in use on South Main Street (CT Route 71) in New Britain, CT. It'll look better when the imagery row on the bottom is hidden.
https://www.google.com/maps/@41.6590093,-72.7780445,3a,49.2y,274.64h,92.9t/data=!3m6!1e1!3m4!1sEn9Yk_wQfiNes36fwH4SVA!2e0!7i13312!8i6656
Nah, but I can note some examples from other cities (at best, my oldest lamps I have in my town date to around the 2000s).
Prior to 2012, I-35E (Dallas, TX) from I-30 to US 67 had old lighting (I estimate about 1980s-can't be from the original opening of the freeway).
CA 110 has some original lighting dating to the opening of the parkway - those lights must have been over CA 11 and US 66 at one point.
A small town here found an old old street lamp pole in the city shed and put it up in the park after repainting it. Looks nice and good little bit of old timey history.
^^ Green Bay did that with a few old light posts into their historical park in Allouez: https://www.google.com/maps/@44.4732773,-88.0305336,3a,75y,86.83h,97.72t/data=!3m6!1e1!3m4!1s4LuTvM54kcTUqQg1E5CrWg!2e0!7i3328!8i1664
Downtown San Diego has done a great job of refurbishing it's original lighting for reuse.
Probably these ones:
https://goo.gl/maps/J49yL3y3h342
They don't look that old, but they are currently being replaced with new street poles with LED lighting.
Here's a nod to some 65+ year old streetlamps in NYC:
http://forgotten-ny.com/2016/01/brooklyn-battery-tunnel-lamps/#comments
My friend Joe used to collect, restore and sell those old lamps to private parties. Numerous communities in the Los Angeles area had them in all styles and sizes, so he had quite a supply.
I'm curious if any of Boston's gas street lamps are "original" lamps from the coal gas era. The ones that predominate now in places like Beacon Hill and Charlestown are supposedly replicas put up from the 1960s onward. There are oddballs here and there, though, that are not really near others. I've wondered about them but have never really studied any of them closely.
Oldest type in Rochester, NY. This one is in Highland Park.
https://www.google.com/maps/@43.1318555,-77.6087518,3a,37.5y,239.95h,81.28t/data=!3m6!1e1!3m4!1sY9wdFz12djQzlKHWu1IJFA!2e0!7i13312!8i6656?hl=en