Some facts for you regarding the shift from undocumented workers to families seeking asylum...

For those apprehended on the southern border:

In 2000, 98% were from Mexico, 2% were from other countries.
In 2009, 92% were from Mexico, 8% were from other countries.
In 2014, 64% were from Mexico, 36% were from other countries.
In 2017, 42% were from Mexico, 58% were from other countries.

In 2013, 87% were non-family-unit adults, 9% were unaccompanied minors, 4% were family units
In 2015, 76% were non-family-unit adults, 12% were unaccompanied minors, 12% were family units
In 2017, 61% were non-family-unit adults, 14% were unaccompanied minors, 25% were family units

Of unaccompanied minors, 77% are from El Salvador, Guatemala, and Honduras; 21% are from Mexico; 2% are from other countries.

Of family units, 94% are from El Salvador, Guatemala, and Honduras; 3% are from Mexico; 3% are from other countries.

Using "intentional homicides" as a proxy for violent crime (from which one might want to flee and seek asylum elsewhere), El Salvador ranks #1 in the world at 82.8 intentional homicides per 100,000 population per year. Honduras ranks #2 in the world at 56.5. Guatemala ranks #15 in the world at 27.3. (Mexico ranks #19 at 19.3 and the US ranks #85 at 5.4.)

So, yes, the data absolutely support the point that US southern border crossings have evolved from almost entirely migrant adults from Mexico to significant numbers of families (and unaccompanied minors) fleeing violence in El Salvador, Guatemala, and Honduras in recent years.