After its conquest of New Mexico in 1846, the United States government upheld the validity of the grant, but subsequent actions by the U.S. did not protect the right to access common lands by the settlers.

Legal disputes and protests, some with violence, between the descendants of the Hispanic settlers and speculators, ranchers, and developers about ownership of and access to land in the grant area were frequent and continued for more than 100 years.

The best known incident was the 1967 occupation of the Rio Arriba county courthouse by Hispanic protesters asserting that grant land should be owned by descendants of the original settlers.

[15][16] Between 1860 and 1865, with the Indian threat declining, Martinez encouraged the first permanent non-Indian settlement in the grant area by conveying small plots of land to 130 Hispanic families totaling about 1,000 people.

His claim to ownership of the land was confirmed by an English-speaking court two hundred miles distant and did not become known to the Hispanic settlers on the grant for nearly seven years.

From 1919 to 1924 "night riders" associated with a shadowy organization called La Mano Negra ("Black Hand") cut fences, burned barns, and threatened the new owners of Tierra Amarilla grant land.

[21] Most of Tierra Amarilla was fenced and in the firm possession of large landowners by 1937 when a tenant farmer named Medardo Abeyta initiated legal action to reclaim access to the former common lands of the grant for heirs to the original Hispanic settlers.

Abeyta founded an organization called La Corporacion de Abiquiu with the objective of removing private ranchers "from the property which had been fraudulently appropriated."

They attempted to make a citizen's arrest of the district attorney, Alfonso Sanchez (who was not present), "to bring attention to the unscrupulous means by which government and Anglo settlers had usurped Hispanic land grant properties."

Three hundred and fifty National Guardsman, armed with tanks and artillery, FBI agents, and New Mexico State Police expelled the occupiers and successfully pursued and arrested Tijerina but in his trial was declared innocent on December 13, 1968.

"[24][25] [26] In 1969, Amador Flores, a resident of Tierra Amarilla, wrote himself a deed and paid real estate taxes for a 500 acres (200 ha) plot of land.

Flores' supporters occupied the land for 14 months until he reached a settlement with the corporation which awarded him 220 acres (89 ha) and cash.

[27] In the 1970s land grant activists stopped plans to build an airport near the town of Tierra Amarilla to encourage tourism.

One opponent of the airport said it would doom the residents to a life of "cleaning up the shit of tourists and hunters who have no respect for our culture and get mad when we speak Spanish."

In 2017, fifty years after the courthouse raid, described as "a watershed moment in New Mexico history," the movement to regain the Tierra Amarilla land by the heirs of the original settlers had subsided, although, according to the Santa Fe New Mexican, emotions were still raw.