Your trees are showing signs of stress and insect problems. We can’t give a diagnosis from photos, i suggest that you call an arborist to come and look at them. 

The second photo looks like it may be Emerald Ash Borer.  If this is the case, you will likely have to remove them. There are treatments available but those are preventative, meaning they have to be applied before that tree has been infested. 

Emerald Ash Borer is present in Dakota County. You don’t say what city you live in, but you may want to contact them to let them know you suspect it in several of your trees. They may have a city forester who will come out to look at them. 

The links below should help you determine if it is EAB and how to proceed.on the UMN page there is a diagnostic tool to help you determine if the trees are ash and if they are infected.

https://extension.umn.edu/tree-and-shrub-insects/emerald-ash-borers

https://www.mda.state.mn.us/eab-info-homeowners