The actual beam? Not far at all to be honest. I actually conducted a small experiment not long ago where I put my 2.1W PLTB450B in a glass mug and fired it up into the sky back in the winter time and walking down the street. The beam itself was very visible when I got out into the street. But as I walking down the street it quickly started to disappear. Now if you want someone to see the beam from a few neighborhoods over, possible even further then you'll need a relatively powerful green lol. My 1045mw 525nm can probably be seen from a quite a ways away. (The beam) I hope this was what you were asking
Aimed at you--brightest
looking 'down the beam'.- second most bright.
from the side - not very far in comparison.
Same power green would be better than blue or red.
under good conditions (low) you can scan clouds.
a special telescope can see some earth lasers from the Moon.
and iirc NASA- 'saw' the laser aimed at the earth left by USA Astronauts .
again by special optics-antenna..etc
I found lasing the clouds of smoke at fireworks shows very interesting.