Route from Indianapolis to Route 66 Trail Heading West?

[JulieScan]

Can anyone recommend a route from Indianapolis to the Route 66 Trail heading west? I am checking for a friend who is trying to get across the country (Philly to San Fran) in 40 days as part of a fundraiser. So we are looking for the fastest, yet safest route (e.g., packed gravel trails or quiet roads). Thanks in advance for advice!

[John Nelson]

I'd just shoot straight down US 36 to Springfield, IL. You'll want to get off US 36 just before Decatur and switch onto county roads. If you're trying to get all the way across the US in 40 days, you need a fairly direct route. BTW, Route 66 goes to LA, so if you want to go to SF, you probably want to switch over the the TransAm/Western Express in Marshfield, MO.

[JulieScan]

Thanks John!