Good question. And it’s an interesting thread on Brooklynian. Here’s one response. I can’t vouch for its accuracy. But the person who wrote it does seem to know a lot.
The answer is Neergard. But it’s interesting to
talk about the other old places. O’Connors bar has an awning which says
"Since 1931," although that would mean it opened during Prohibition. I
remember a NY Times article saying that the O’Connor patriarch came
over from Ireland to start up his bar in 1933. Triangle goes back to
the ’40s – but didn’t it used to sell dry goods? The Mega Glass space
has been a glass shop under different names since at least the 1930s.
Steve Belsito & Sons (plumbing/heating) claims "Est. 1925," but I
don’t think they’ve been in the neighborhood all that time. Great
Western Fine Foods goes back to the 1930s at least. Leopoldi Hardware
goes back to 1966 but before then it was Fazio Bros. Hardware (check
out the art deco "hardware" sign on the second floor). A&S claim to
go back to 1942. Jackie’s 5th is a relatively recent name, but the bar
was Costello’s in the 1940s and numerous other names in between.
Tarzian is very old indeed – 1920s at the latest. Smith’s Tavern has
been in business under that name since the 1930s, probably right after
Prohibition ended. Same goes for Farrell’s. Garry jewelers opened in
1951 according to their sign. Lenny’s Pizza (5th Ave. & Prospect
Ave.) dates back to 1954. I believe the oldest continuously open
restaurant in the Slope is El Viejo Yayo on 5th Ave. near Dean,
although it used to be called Blanco’s and it was owned by a Cuban
family before a Dominican family bought it; it supposedly opened in
1963.
In terms of owned-and-operated by the same person, we should
mention Tony at the Record & Tape Center on 5th Ave. & 9th St.
He’s been running that place since 1972 and it had a former incarnation
up the street a few blocks in 1968-1972.
What about Purity and Daisy’s Diner? Purity has moved locations and changed owners but I believe it first opened in 1929 when it was on 7th Ave and Union St where the real estate ageny and tutoring place are. Also, Daisy’s Diner on 5th Aven between 9th and 10th streets I believe opened in 1935 but was originaly a German owened ice cream parlor… Not quite as old as the the barbershops previously mentioned, but Josephs (also on 7th Ave and Union) has been around 40 years I think. He has some photos taped to the wall on the right when you first walk in.
The Park Slope Barber Shop, on Seventh Avenue between 3rd and 4th streets, goes back, in various incarnations, more than a century – all in Park Slope. It is probably only slightly younger than Neergaard. The barber shop’s current owners (since 1948) claim it began in 1903 (which according to the blog “Jeremiah’s Vanishing New York” would likely make it the oldest existing barber shop in New York). And Henington Press, one of the few remaining letterpress print shops in New York, has been in the same location on Sixth Avenue between 11th and 12th streets since 1912, and is owned by the grandson of the founder.
zuzu’s petals…the flowershop formerly known as Growingthings ..was opened in january 1972 in the back of a hatian bookstore on flatbush avenue by veronica prilaux. she moved to seventh avenue between berkeley and lincoln in spring of 1972..the spaces now occupied by marty’s la tacqueria….in march of 1974 she moved to 81a 7th avenue and sold the business to me in august of 1974. i was the manager of the shop from november of 1972.