On advertising and mass transit

Perhaps other denizens of the area can back-up my observations, but I've noticed that the advertising is different depending on the Metro line that you're actually riding. Most of my commuting involves the Red and Green lines, both of which run through the District and into Maryland at their respective termini. On these lines, the advertising seems rather run of the mill - social services, job opportunities, etc. However, when I ride the Orange or Blue lines, which both run into Northern Virginia, the ads are more geared towards the national security side of things, informing me of the right logistics platform for supplying an Army division or the benefits of a certain type of cargo plane. I get that NoVa is heavy on the Defense types, but I just wanted to make sure I wasn't imagining things.

Added bonus observation: One of my favorite ads is for a school offering Master's degrees in strategic defense policy, promising to train students in any number of sub-fields of "ethical warfare" (the oxymoronic nature of which I won't touch). One of the fields students can specialize in is "political economics," which I'm fairly certain means something different to them than to us social science types. I doubt the Grundrisse is on their reading list.