While driving around Delaware during the holiday weekend, I saw signage on DE 1 northbound indicating that DE 16 continued east on Broadkill from DE 1, rather than ending at DE 1 as the HB has it. There is also a DE 16 reassurance marker on Broadkill Rd. eastbound just east of the DE 1 intersection. There's no other route signage on the ~3.7 miles of Broadkill Rd. between DE 1 and its end in Broadkill Beach. Nor is there any signage on DE 1 southbound, or DE 16 west of DE 1, confirming that DE 16 extends east of DE 1.
The online mapping is inconsistent on how far east DE 16 goes. The state highway map I picked up at a visitor center isn't clear either, other than to change the line on the map for Broadkill Rd. from red west of DE 1 to black east of DE 1.
I'm comfortable extending DE 16 east to Broadkill Beach. I can make the change myself (would only need to add one point to the DE 16 route file), unless someone disagrees.