After the revolt, he headed east on the Santa Fe Trail where he worked for Kansas City, Missouri founder John Calvin McCoy at Westport, Kansas City and Independence, Missouri.

During the Mexican–American War in 1845, he was engaged by a sutler to be an interpreter for the United States Army.

When the troops were dispatched to Santa Fe, Ceran St. Vrain dispatched Abreu in advance to buy up the goods of competing sutlers for St. Vrain so it could enjoy a monopoly with the United States.

Abreu worked in a store for St. Vrain in Santa Fe, and worked as an interpreter for the United States and in the winter of 1848–49 delivered the U.S. mail between Santa Fe and Fort Leavenworth, Kansas (a process which took 40 days).

"[3] The family sold most of the ranch in 1911 after his death and was bought by Waite Phillips in the 1920s, who was to donate 35,857 acres (145.11 km2) to the Boy Scouts of America in 1938.