Editing Interstate Highway System (section)

===Chargeable and non-chargeable Interstate routes===
Interstate Highways financed with federal funds are known as "chargeable" Interstate routes, and are considered part of the {{convert|42000|mi|km|adj=on}} network of highways. Federal laws also allow "non-chargeable" Interstate routes, highways funded similarly to state and US Highways to be signed as Interstates, if they both meet the Interstate Highway standards and are logical additions or connections to the system.<ref>{{usc|23|103(c)}}, Interstate System.</ref><ref>{{USPL|99|599|Surface Transportation Assistance Act of 1978}}</ref> These additions fall under two categories: routes that already meet Interstate standards, and routes not yet upgraded to Interstate standards. Only routes that meet Interstate standards may be signed as Interstates once their proposed number is approved.<ref name="FHWA2">{{cite web |first = Tony |last = DeSimone |url = https://www.fhwa.dot.gov/planning/national_highway_system/interstate_highway_system/routefinder/?redirect |title = FHWA Route Log and Finder List: Additional Designations |publisher = Federal Highway Administration |date = March 22, 2007 |access-date = January 4, 2010 |archive-url = https://web.archive.org/web/20140805032748/http://www.fhwa.dot.gov/reports/routefinder/#s06 |archive-date = August 5, 2014 |url-status = live }}</ref>