Because all US-based launches are done over the ocean. Whether it’s KSC or Wallops which launch to the east over the Atlantic, or Vandenberg which launches south over the Pacific.
They fly the rockets over the ocean.
Vulcan launched from Cape Canaveral Florida. This is the launch site that the Apollo and Space Shuttle programs used. If you’re trying to reach an equatorial orbit, the rocket will launch eastward. Cape Canaveral is a great choice for these launches because the rocket will fly over the open ocean, away from the people they might endanger.
Launch sites are located in places where there aren’t many people in the direction they intend to launch.
As others have mentioned, most launch sites are on the coast of countries. Notable exceptions are Russia’s lease of the kazakhstan’s Baikonur Cosmodrome and China’s Xichang Satellite Launch Center and Taiyuan Satellite Launch Center. A quick google shows at least one whoopsie from the former. It’s also one of the reason France maintains French Guiana as a department of France, it’s right on the equator and on the ocean. IIRC that’s where the JWST was launched
Lol, a “whoopsie”. That’s pretty horrible though.
And it’s not just one “whoopsie”. It’s a semi-regular occurrence in China. CASC had another “whoopsie” just last month: https://spacenews.com/china-launches-new-beidou-satellites-rocket-booster-lands-near-house/
Firstly, the US launches over the ocean. Some other countries can’t / don’t bother, and often drop bits of rockets near people which is generally considered a bit rude.
Secondly, there is an exclusion zone underneath the rocket’s flight path and they won’t launch if they pick up a ship or plane in that zone. Governments publish that exclusion zone through specific channels - Notice to Airmen, and Notice to Mariners - with warnings to steer clear of the area at specific times.
Pilots and ship’s captains should check for notices before heading out - for commercial operators this is part of their everyday checklist.
