To drive from Twin Falls, Idaho to Longview in Washington, it will take approximately 9 hours and 51 minutes (on average, driving responsibly, fuel & food stops etc.) with a distance of 596 miles if you follow the I-84 going west.
7 hours, 45 minutes to drive from Washington DC to Buffalo NY, then another 20 mins to get to the Falls.
19 to 20 hours
Given is the calculated distance as well as the driving travel time, which does not take into account driving conditions, traffic, etc. The distance between Boise, Idaho and Longview, Washington is 469 miles. The resulting travel time is 7 hours and 49 minutes.
9 hours
About 3 hours
21 hours
6 hours and 21 minutes
23 and 1/2 hours
Google Maps estimates the driving time as 11 hours and 7 minutes.
roughly 18 hours
from Washington DC to Niagara Falls NY is 7 hours 44 min (infor from mapquest.com)
Google Earth cites the distance from New York to Niagara falls as 411 miles, and Niagara Falls to Washington DC as 406 miles. That's a total of 817 miles, and a total driving time of 14 hours 8 minutes.