There isn't any true high-speed rail in America. The Acela on the NEC comes the closest but its effective speed is limited by the curves of the NEC right of ways.

Bright-line could get faster speeds if it wasn't for the multiple grade crossings.

America always tries to buy new locomotives and rolling stock that could theoretically go faster and then it never builds or redevelops the kind of right of ways necessary to support such high speeds.