I could have phrased that better. Most of the population in San Diego County has 619 area codes.
Five years ago, they were warning about running out of numbers (7.7 milllion possible combinations), and began an 858 overlay for new lines that would have normally been 619. The CPUC calls it a "boundary elimination overlay"---meaning that now, if you were in San Ysidro, they'd probably give you an 858 number.
The point being that this was a 619 area code that another poster mentioned and it's San Diego County.