Where in North America is area code 435?

Salt Lake City and the urban core of Utah use area codes 801 and 385.

The 801/385 area code includes Alta, American Fork, Bountiful, Clearfield, Farmington, Goshen, Holladay, Kaysville, Kearns, Lehi, Magna, Midvale, Morgan, Murray, Ogden, Orem, Payson, Pleasant Grove, Provo, Salt Lake City, Sandy, Spanish Fork, Spanish Fork Canyon, and Springville.

The rest of Utah is area code 435.
The 801 area code and 385 area code cover the Wasatch Front in northern Utah. This includes the counties of Davis, Morgan, Salt Lake, Utah, and Weber.