Further south matters. Basically, from the earth's rotation, you get 1000 MPH x cos(lattitude) of free velocity toward orbit, so being closer to the equator is a fairly big deal.
The worst case is Israel, which for geographic and geopolitical reasons has to launch to the west instead of east. Even that's only about a 30% penalty in payload. https://en.wikipedia.org/wiki/Israel_Space_Agency#Palmachim_...
Also, for spent stages, the population density of Kansas isn't that much higher than the Atlantic, they're basically identical after rounding. /s
The lawsuits are $0, after rounding to the nearest trillion.
Exactly so!
Wait, you caught the sarcasm tag right?
If you're going for something highly inclined then it doesn't matter at all. Launching to the ISS from Baikonur is no more costly than launching to the ISS from Canaveral or Guiana. Launching into a high equatorial orbit, like for a comsat, is far more costly because you can't naturally achieve an inclination lower than the latitude of the launch site, so you need an expensive plane change. If you wanted to launch into a low equatorial orbit for some reason then it would be even worse, and the high-latitude launch sites would become impractical.
And actually, Israel is far from the worst case. The worst case would be something like launching into an equatorial orbit from a site at one of the poles. This would require something like 25-30% more delta-v, which because of the rocket equation means vastly more rocket for the same payload. But for a polar orbit, launching from the poles would be fine, actually very slightly better than an equatorial launch site because you wouldn't have to cancel out the speed you get from the Earth's rotation.
That said, I pointed out that Israel has geographical and geopolitical difficulties, which force them to launch to the west rather than east. Would it be harder for Israel to place something in GEO from Palmachim, which must first travel west over the Mediterranean before going east, or for Sweden to place something in GEO from Esrange, which requires a plane change?
(I'm trying to be somewhat realistic. I think Esrange is the most poleward launch facility, though they only do suborbital. Otherwise, consider a possible Norwegian launch facility on Svalbard.)
Anyway, the penalties can be pretty big, but they're often tolerable. For GEO you want minimal latitude, for others latitude may not matter at all. But other considerations (like Israel having land to the east) can easily override the penalties.
For the particular example discussed here, if you could ignore the problems with squishing people and buildings downrange, Colorado would make a decent launch site. KSC's latitude is better, but it wouldn't be a huge deal. You'd even get at least a little bit of it back because you'd be launching from higher altitude.