Interestingly, there is one place in the USA where high speed rail has a chance: the Dallas/Fort Worth-San Antonio-Houston triangle. There is a LOT of business travel between these three cities (plus Austin between Dallas and San Antonio), and the airlines plus the Interstate freeways between these three cities are already running at effective capacity now. This is where the Texas Central Railway proposal comes in: it will use the international version of the 700 Series Shinkansen trainset (N700-I) for trains travelling at 330 km/h (205 mph) to travel initially between Dallas/Fort Worth and Houston, with eventual extensions to form the triangle of routes (e.g., adding Houston to San Antonio, San Antonio to Dallas via Austin). Because it uses "off the shelf" high-speed trainset technology already in use on Japan's Shinkansen network and the fact the topography between Dallas/Fort Worth, Houston and San Antonio does not require building through mountain ranges (e.g., a lot of tunneling work) or extensive need for earthquake safety mitigation, construction costs on a per-mile basis will not be ridiculously exorbitant like the California system will cost.
Imagine Dallas/Fort Worth to Houston in 90 minutes, Houston to San Antonio just under an hour, and San Antonio to Dallas/Fort Worth in around 105 minutes.
It sounds like a crazy idea, but remember this system is designed primarily for business travellers, the people most likely to use them. After all, in Japan on the Tokaido Shinkansen line between Tokyo and Osaka, most the the passengers travel on business, and as such the Central Japan Railway Company (which operates the Tokaido Shinkansen trains) enjoys healthy profits from such a steady stream of passengers.
What about the cows?
Texas is so big vast and has no everglades or Miami lawyers to bog down the situation high speed may be a possibility there, never in Fla. Much of Fla. is barely 100 miles wide.
If the lawyers didn’t kill it the enviros would. Besides everyone uses cars down here. Some never leave their auto.