Following redistricting ahead of the 2022 election cycle, the 18th district was relocated to the San Gabriel Valley.

Due to redistricting after the 2010 United States census, the district shifted east within Los Angeles County and includes portions of Burbank and Glendale.

The 28th and 34th are partitioned by Colorado Blvd, Lantana Dr, Church St, Adelaide Pl, Highway 110, N Huntingdon Dr, S Winchester Ave, Valley Blvd, Laguna Channel, Highway 710, l-10 Express Ln, Rollins Dr, Floral Dr, E Colonia, Belvedere Park, Highway 60, S Atlantic Blvd, and Pomona Blvd.

The 28th takes in the north side of the cities of Glendora and Monrovia, part of the city of Pasadena, the cities of Alhambra, Monterey Park, Arcadia, Glendora, Rosemead, San Gabriel, Claremont, Temple City, La Cañada Flintridge, South Pasadena, San Marino, and Sierra Madre as well as the census-designated places Altadena, South San Gabriel, East San Gabriel, East Pasadena, San Pasqual, and La Crescenta-Montrose.

The 28th district takes in the north side of the cities of Upland and Rancho Cucamonga and the census-designated places San Antonio Heights, Lytle Creek, and Wrightwood.