You need to expand your horizons.
Orange $1000 cash chips are required in casinos located in Connecticut, Indiana, Illinois, Iowa, Louisiana, Michigan, Minnesota, Mississippi, North Carolina, New York, New Jersey, Ohio, Wisconsin, among others -- and pretty much every single US state east of the Mississippi River that allows gambling, except Missouri. Many of those jurisdictions require a yellow $20 chip, hence the requirement for an orange $1000.
Nevada doesn't have hard color requirements for cash chips, but at least a dozen Vegas casinos currently use (or have used) orange cash $1000 chips. Some Nevada casinos have used both orange and yellow for $1000 chips at one time or another.
Here are just a few orange $1000 cash chips from casino chip sets commonly seen around here on PCF:
Along with some other recognizable brands from Nevada and elsewhere:
So yeah, most cash $1000 chips are orange in the USA. And yellow is the most common color for T1000 tournament chips.