When did states stop producing button copy Interstate shields?

[PurdueBill]

I recall that the westernmost end of I-70 in Ohio was renovated in about 2000 and by 2001 the new signage was up and was all reflective sheeting.  I wonder if the 670 signage was ordered before a changeover was made, or if it was done by ODOT region.    I definitely recall one-off replacement I-shields in full button copy, border and all, replacing failed shields on old signs all the way into the late 2000s in Summit County--then the whole sign itself getting replaced a year later.