up this river

[IMPSX-UE]

Michael: I'm looking for someone. Guy named Lincoln Burrows.
Prisoner:Linc the Sink?
Michael: That what they're calling him now?
Prisoner: Yeah. As in, he'll come at you with everything but the kitchen...
Michael: Where can I find him?
Sucre: Man killed the vice president's brother, and in a month, he's getting the chair, which means no one up this river is more dangerous than him, 'cause he's got nothing to lose now. What are they gonna do? Kill him twice?

(Hi! What does "up this river" mean? How do I interpret "up" in this context? Could you have a look for me? Thanks for your help. )

Michael: There a way I can get to him?
Sucre: Oh, no. The only time those boys get out is for chapel and P.I.
Michael: P.I.? What's that?|
... ...

[Charlie Bernstein]

The Sing Sing Correctional Facility is a maximum security prison in Ossining, New York. Ossining is up the Hudson River from New York City. So New York criminals call going to Sing Sing "going up the river."

[IMPSX-UE]

The Sing Sing Correctional Facility is a maximum security prison in Ossining, New York. Ossining is up the Hudson River from New York City. So New York criminals call going to Sing Sing "going up the river."

Hi, Charlie Bernstein,

Thanks for your kindness.

I do not get the "up" in the sentence you wrote down - " Ossining is up the Hudson River from New York City."

May I get it as "Ossining is at (up) the Hudson River from New York City." Does "up" actually mean "at" in this sentence? Thank you.