Thanks for your question.

Bark splitting on a honey locust tree is common and can be caused by several factors, including:

1). Rapid temperature fluctuations, especially in late winter or early spring, can cause the bark to split.  This is called sun scald.  It occurs when the bark heats up on sunny winter days and then rapidly cools, causing the bark to crack. If this bark splitting on your honey locust has been going on for a few years, I suspect that winter sun scald is the cause. This is quite prevalent in honey locusts.  If this splitting is just minor, as seems to be the case with your honey locust, there should not be any serious threat.

2). Physical damage from lawnmowers, string trimmers, or other equipment can cause bark to split. The splitting that you see is a bit too high up on the trunk to be attributable to this cause.

3). Roots that encircle the trunk can cause pressure and lead to bark splitting. These are called girdling roots. This often occurs when a tree is planted too deeply. This might be your situation, although it is rather rare with honey locusts. If you wanted to check on this possibility, carefully remove the soil from around the base of the locust until you can see roots coming out from the trunk. If they are growing in a circular manner around the tree, these are girdling roots. See the following for remedial procedures:

https://www.missouribotanicalgarden.org/gardens-gardening/your-garden/help-for-the-home-gardener/advice-tips-resources/insects-pests-and-problems/environmental/girdling

https://williamson.agrilife.org/files/2011/07/girdling_roots_3.pdf

The bark cracks in your honey locust appear rather minor at this point so I don’t believe that there should be great concern on your part. However as a precautionary procedure, wrapping the lower three feet or so of the trunk would be wise. Wrap high enough to cover all existing splits. Do this in November and remove in late March or early April. See the following for more details:

https://extension.umn.edu/planting-and-growing-guides/protecting-trees-and-shrubs-winter - sunscald-1263860

https://www.ndsu.edu/agriculture/extension/extension-topics/gardening-and-horticulture/trees-and-shrubs/how-wrap-trees-winter

Good luck. Please get back to us with any additional, related questions. Thanks for using our forum.

Glad to be of assistance.  Good luck with your honey locust and thanks for consulting us.