That's a good point; I later looked at Lumen's network map (https://www.lumen.com/en-us/resources/network-maps.html) and saw there was a link between iad and pit. But even if you have a network link, you do need diversity. I've seen examples where an ISP decided to do maintenance in Chicago, shutting down all their peering with us in the metro; all those users we served there then transited peering in DC, where their next closest peering point was. Unsurprisingly, their users had a bad time.

> How much of that is inside the datacenters? I would expect extra and slower hops for servers as compared to data bouncing from one trunk to another.

We generally attribute less than 1ms for all the links between datacenters within the same metro area. Neither iad nor lga are exceptions to this.

I ran a traceroute just now and the the backbone hop between lga and iad was ~4.8ms. So, better than 6ms, but still not 3.6ms which you'd expect from 450 miles / (2/3*c), and definitely not the < 2ms you claim. And we're certainly not transmitting this over copper, which would get you pretty close to full speed of light but at the cost of far lower bandwidth.