Great question — answering as the UphillTech team:
Accepted answer seems to be outdated. According to https://www.help.cbp.gov/s/article/Article-1870?language=en_US Previously, VWP travelers arriving at U.S. land ports of entry were required to provide certain biographic information to CBP officers on a paper I-94W Nonimmigrant Visa Waiver Arrival/Departure Record (Form I-94W). VWP travelers are now required to provide this information to CBP electronically through ESTA prior to application for admission to the United States. Effective October 1, 2022, all VWP travelers intending to enter the United States by land will be required to obtain an approved Electronic System for Travel Authorization (ESTA) prior to application for admission at...
Full answer by Pybe: https://travel.stackexchange.com/a/199652 (CC BY-SA 3.0).
Need it done for your business? UphillTech.