So here's a question that I've always traditionally been tripped up on, what is the official spelling of "railroad" for LIRR and MNR? It's similar to the Berenstain Bears affect where it's sometimes known as "railroad" while other times it's "rail road".
What makes this even more interesting is the MTA normally refers to the LIRR as The Long Island Railroad, but rather refers to Metro-North as Metro-North Railroad, making this whole situation even more out of the ordinary.
While both terms are socially acceptable, in this case, it's technically correct to say Rail Road for LIRR and Railroad for MNR.
And more facts on the name, It's worth remembering that the Long Island Railroad (oops Rail Road) is the single longest-running Class 1 rail operation that is still operating in it's original name in the United States. So, it could be considered the longest running railroad, which is pretty cool considering it's also the busiest!
So, if one day, you feel like leaving out the space of the LIRR's name, just remember that "rail" and "road" is two separate words when it comes to the LIRR!