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Correct, and this time of year you get about 45 minutes of twilight, so by 5:00 PM it's pretty dang dark. Technically though, there's even some light left in the sky on a clear day for about another hour after the end of twilight.
Until I got serious about photography, I had no idea how complicated it really is. Sunset's when it gets dark, right? Well, no... Sunset is when the sun drops below the horizon, based on a horizon level with your viewpoint. Obviously it doesn't go pitch black instantly. So you have "civil twilight" or as photographers like to call it "blue hour". At the end of that, most folks would agree it's dark. But then you have "Nautical Twilight", when the sky is deep purple, and after that you have "Astronomical Twilight", when there's still just a tiny touch of light in the sky. You won't notice it unless you're using a telescope or doing astro-photography.