Yes, it's a New York/New Jersey thing to say 'on line'. Although 'in line' appears to be used in this area also. I've never heard it anywhere else (presumably it spills into other parts of the North East US). 'In line' is the accepted term. 'On line' or 'online' is interpreted as 'using the internet' throughout the rest of the English speaking world.
0 The " on line " thing came about because of the Ellis Island experience. Imigrants literally stood on lines painted on the floor to move from one station to the next. The idiom remains in the NY area until this day. 0-
0 wait on line is used in New York City. Example, "are you waiting on line?" to someone who looks like they are in line for .... the bus, to purchase a movie ticket, checkout, etc.0-