8 October 1957, New York Times, pg. 37:
PLANNED BY CITY
Rule Will Enforce Drive for
Safety Education After
Program Is Under Way
STRONG ORDINANCE DUE
Mayor's Committee Named
--Slogan to Be "Cross at
Green, Not in Between"
By JOSEPH C. INGRAHAM
The committee saw several advertising and promotion ideas and listened to a seven-word slogan that is to set the keynote for the drive. It is:
"Cross at the Green, Not in Between."
18 November 1957, New York Times, pg. 1:
The year-long attempt to educate pedestrians to "cross at the green not in between" will be touched off by city officials at Forty-second Street and Fifth Avenue at 11 A. M. At the same time, the police said they would start to bring motorists to book for flagrant violations of the pedestrian's right-of-way.
21 December 1964, New York TImes, pg. 25:
IN SPANISH POSTED
New York City Law
Cruce En Las Esquinas
Obedezca Las Luces De Trafico
Obedezca A Officiales Policiacos
Cruce Con La Verde...
En El Medio Pierde
Translated, the Spanish means: Cross at the corners; obey the traffic lights; look both ways; obey police officers and (roughly) cross at the green, not in between.
I belive this slogan was crafted by then advertising executive John Temple-Raston