As a citizen of a VWP country (The Netherlands), I do not need ESTA to enter the USA by land:
If you are a citizen of a country that participates in the Visa Waiver Program (VWP), and you enter the U.S. by land from Mexico or Canada, you are only required to complete the paper I-94W form at the land border crossing. ESTA is currently required for air and cruise ship travel only.
If I arrive to Windsor, Ontario at 11:43, can I catch a Greyhound bus from Detroit departing 14:00?
The tunnel bus departs every 30 minutes from the Windsor International Transit Center (3.5 km from the VIA Rail station), and takes slightly over 30 minutes to reach various stops in Detroit, so under normal circumstances, it would be no problem. However, there's a border crossing in-between. How much extra time should I take for crossing the Windsor-Ontario border on the tunnel bus?
(Note: I chose to ask a very specific question to a quite specific border crossing, but more generic answers are also welcome)