"The United States Federal Aviation Administration defines an ARTCC as
Government - National - USA, Transportation - Aviation
[a] facility established to provide air traffic control service to aircraft operating on IFR flight plans within controlled airspace, principally during the en route phase of flight. When equipment capabilities and controller workload permit, certain advisory/assistance services may be provided to VFR aircraft. An ARTCC is the U.S. equivalent of an Area Control Center (ACC)."
This map shows the Fort Worth ARTCC which is responsible for high-altitude enroute traffic in a large area of airspace as far west as eastern NM, as far east as northern LA, as far north as Oklahoma City and as far south as Waco.