I would tend towards the treadmill as getting an accurate watch measurement while running on a treadmill can be hit or miss. Also, most treadmills now have a sync to your watch, use that instead of another app.

Half fanatics has a list (although not a complete one) of half marathons going on all year round. There is also runners world, which has a pretty extensive list of half’s.

Ran the palmetto peach 10k this past Saturday and had a great time. Question: there was a pretty significant discrepancy between my Apple Watch (series 7) and my chip timed run. Anyone have an issue with their watch being off? It was a 3 minute difference and roughly 3 tenths of a mile between the two.