It has been a while since I have been to any downtown area including Denver, so I do not know how the rest of the country is going.
Today, the city of Denver is beginning installation of 4,500 new replacement parking meters.
The new meters take coins, credit cards, and prepaid parking cards purchased from the city.
Waldo, I noticed the last time were downtown in Wichita that they still had parking meters, the meters took coins only. This was in mid 2009. I have been downtown in Tulsa but I haven't paid any attention as to if they had parking meters or not..
The parking meters by the Wichita Public Library still take just coins.
Not too many years ago, I had to put coins in a Denver parking meter and thought much progress had been made because the meter device was no longer mechanical but was digital with a liquid crystal display to show the time being purchased and the time left. I suppose that meter maids, or meter butlers, would have to not only monitor the time on each meter, but also the remaining battery capacity.
The only coin those machines would take was a quarter and I had to put in several for a two hour stay.
I recall in my home time that a penny would buy a comfortable number of minutes of parking time. A nickel would get a lot more time. I think those were the only two coins it would take. And, if you had to put in a number of nickels, parking was getting expensive.
Oklahoma City, of all places, installed the first parking meters in the US back in the 1930s. It was the first city because that is where it was invented.
I was in Wichita in January and had to feed the meter... it only took nickles and dimes and of course all I had was quarters. The guy in the shop told me I'd better not take a chance, so he gave me some change. It's been a long time since I've used a parking meter!