Because of some construction that will be done in my backyard, I have to move Echinacae and Rudbeckia plants now. I also have a Marsh Milkweed that is in danger. Does anyone have any suggestions for reducing the shock? Do milkweeds have a tap root?

I have always found to transplant anything do it late in the evening and
try to get as much dirt around the plant as you can. Already know where
you are going to put it and water the new hole real good. I've always had
good luck transplanting in the rain if the weather would cooperate with you
It's messy but the plant responds well in damp weather. The two plants
you are talking about are very hardy anyway.Good Luck!

Thanks for responding. I transplanted all with the exception of one Purple coneflower that is massive. That one will be moved pretty soon. I predug my holes and got as much dirt as possible. I did all this on Friday afternoon when I heard the weather forecast called for a chance of rain. So far, all look great. The nice part is I found about 20 purple coneflower seedlings that I dug up and potted. They have found their way to my sister's new house. Which is really cool, because I dug the original coneflower's and Rudbeckia from her old house. I transplanted them and some heirloom iris when she sold the house.
The marsh milkweed still needs to be moved also.

Water, water, water.

They might not bloom this year, and even mostly die off, but I'll bet that next year or the year afterwards, they do well.

I've had to transplant in the middle of summer before, it was ugly but they got through ok, after a couple of years of not doing anything much except shooting up green leaves.