Final answer:
Oil, cotton, and cattle dominated the land-based economy of post-Reconstruction Texas and are still important today.
Step-by-step explanation:
The element that dominated the land-based economy of post-Reconstruction Texas and is still important today is oil, cotton, and cattle. Cotton, as mentioned in the antebellum era, became the major commercial crop of the South, surpassing other crops like tobacco, rice, and sugar. By the year 1860, the South was producing two-thirds of the world's cotton. Oil, on the other hand, became a dominant industry in Texas in the middle of the 20th century.
Texas, along with Pennsylvania and California, became one of the leading oil exporters worldwide. Cattle, specifically longhorn steers, played a significant role as well, with demand for their meat in eastern markets leading to the era of cowboys and cattle drives.