 Hacienda Heights is the second largest census designated place in Los Angeles County by area and the county's second largest CDP by population.During Spanish rule, Hacienda Heights was a part of Rancho La Puente, which was operated by the nearby Mission San Gabriel Arcángel in San Gabriel.The Rancho was eventually acquired by John A. Rowland and William Workman in 1845 via a Mexican land grant, and eventually acquired by Elias "Lucky" Baldwin.