It's not clear what "Northern Short Line" you're talking about, but no, it's not.
The properties in the US (original) Monopoly are named (mostly) after locations in Atlantic City. However, there was no railroad there named "Short Line." It was probably named after the "Shore Fast Line." It's also possible that it was named generically; "short line" is a generic name for a local rail line.
reading railroad, Pennsylvania railroad, B. & O. railroad, short line railroad
They are: Reading Pennsylvania B. & O. Short Line
Reading, Short Line, B&O and Pennsylvania.
Reading,Pennsylvania,B&O,and Short Line Railroad
Reading, Pennsylania, B&O, and Short Line
In a traditional Monopoly set, the railroads are Pennsylvania, Reading, Short Line, and B&O. Other sets are different, because they are customized for different countries and languages. Some are customized for cartoons and don't have railroads at all.
The first railroad on the Monopoly board is the Reading Railroad. It is one of the four railroads featured in the game, along with the Pennsylvania Railroad, B&O Railroad, and Short Line. The Reading Railroad is located in the yellow property group, specifically between the Chance space and the International Space.
B&O Railroad, Short Line, Reading Railroad, Pennsylvania Railroad. Source: http://en.wikipedia.org/wiki/Monopoly_(game)#Atlantic_City_version
no
Northern line was created in 1890.
There are several web sites that claim to have free monopoly on line. A Google search for "monopoly online" should provide you with several choices.
There are 28 in total : 22 properties 2 utilities (Water Works and Electric Company) 4 railroads (Reading, Pennsylvania, B&O, Short Line)