i guess there should be an additional question: to what scale maps are you interested?
most usgs maps are 20-30' contours. the generated map link i posted will generate maps to any scale. keep in mind that the quality of maps depends on the database used (1-arc, 1/3 arc, or 1/9 arc).basically, 1/3 arc has 10' vertical accuracy and 1/9 arc has 3' accuracy. they are also reportedly updated annually, but i have seen instances where i would argue that it is not. as always, use any map with caution and confirm the map correlates with field conditions.