Out of curiosity, why do you frequently need to know your altitude? I don't think I've ever known my altitude except when driving past those "Welcome to Springd

Out of curiosity, why do you frequently need to know your altitude? I don't think I've ever known my altitude except when driving past those "Welcome to Springdalevale, pop. 781. alt. 2,003 ft" signs you see when driving through small towns in mountainous areas.