I am close enough to NYC to get a feel for the way Trump talks.
NYC people sometimes (not all times) have a certain accent. It is well known, and well mocked. Think: Fuggetaboudit.
I guess Trump has a certain form of this accent. You can tell by listening to it that he has spent time in the area.
But there is another facet to the way he talks that has nothing to do with where he was born and lived.
It's a "fake tough guy" accent, and it has to do with insecurity. I saw a clip this morning where he was talking about the NFL, and how the game is not like what it used to be. He was implying that safety rules have ruined the game. Something like...Those hits! In the old days, they could hit! Now they can't hit! Some bullshit like that.
I found this really interesting. I watched his body language. I noticed how he replaced the "t" sound with a "d" sound. Not exactly a natural NYC accent, but rather, more like a douchebag trying to make himself sound tough. I'm really familiar with this act, as I'm sure you may be. I'm not sure if people in the mid-west, for example, experience this, but it's very common where I live.
This "accent" is not really an accent, it's more of way to verbally try to make yourself sound like someone you are not.
I'm probably not explaining myself very well here, but I found that clip this morning telling and interesting.
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People visit North Carolina for 3 days and come back talking like someone in Gone With the Wind. 
Not on TV, of course, but I've always been a bit of a linguistic chameleon and I did spend some small amount of time in the South.
I grew up with a lot of guys that talked like that. Thing is though, they were legitimate tough guys. A few are in prison now for violent crimes, including murder.
That's why it seems so funny to me to hear Trump speak like that. He's a doughy fucker that would curl up into a ball before actually physically defending something he loved. 
