We too had great trouble finding a test site that could get us results in 24 to 48 hours.
We traveled from Lewiston NY to Port Huron MI through Canada today, our second passage through Canada.
First off, forget about the pharmacies unless they specifically offer a "Rapid PCR" test (mostly found in very large urban areas); otherwise expect 4 to 6 days from pharmacies. The Vermont state sponsored fast test test sites are only for limited hours on limited days. None along I-91 from St. Johnsbury to Brattleboro were open on Sunday. Nor were any sites offering 24-48 hours in Greenfield, Amherst or Northampton MA on Sunday. The Monday to Saturday fast sites in Amherst and Northampton required a referral from your doctor!
On weekday mornings, from 7 am to 1 pm walk in sites at Holyoke Community College and at Greeenfield Community College were offering rapid tests. We got ours in Holyoke and the results were available 23 hours later. The next day we began our return journey
In Canada, most PCR test results are available within 8 to 24 hours - if only we could cross the border to get the test.
The ArriveCan app, which is required, I believe, is indeed clunky, and you have to reenter everything for each crossing, but it does make it quite smooth at the border. See https://www.wanderth...rder-on-aug-26/ for more info on filling out the app.
On the plus side, no long lines at the border. Along with the usual questions coming into Canada at Queenston, we had an interesting and enjoyable conversation with the border agent on other topics - there was no one in front or behind us.