https://www.api.org/oil-and-natural-gas/wells-to-consumer/transporting-oil-natural-gas/pipeline/where-are-the-pipelines
2.4 million miles of hydrocarbon pipelines in the US.
That huge blob of crude oil lines in north central Oklahoma is Cushing. Cushing is the largest crude oil pipeline hub in the US. Enormous storage capacity there. Why Cushing? From about 1900-1940, huge oil fields around Cushing, ie. Osage County, Glen Pool and Seminole. Pipelines snaked out to the east, northeast and south to get to the big refineries.
Not mapped at all are the pipelines in the Gulf of Mexico. You can get a sense of that network looking at the pipelines at the Mississippi River delta extending west to Galveston Bay.