Philadelphia-New York City is one of the most important corridors in the US as it is a pair of cities that are just 90 miles apart and are the 6th and 1st largest cities in the country respectively. And luckily they have good transit connections

The train travel times between the 2 cities varies between about an hour and 10 minutes and an hour and 50 minutes

Additionally there are a total of 48 amtrak trains that go between the 2 cities daily and 48 more NJ Transit Trains between NYC and Trenton where you can then transfer to a train from Philadelphia to Trenton that take about 2 hours and 30 minutes includingthe transfer.

Basically of all major city pairs in the US, none have better connectivity than Philadelphia and New York