I love to visit museums when I travel – so interesting and you get to experience more of the local culture.
I found this great free website, http://freemuseumday.org/cities.html that lists major US cities and each city shows the days that the museum is free in the town.
I found out that at the Seattle Children’s Museum the last hour of every weekday (4:00pm – 5:00pm), they accept any amount of payment for regular admission to the Museum. Your family simply pays what you can afford to enter and play.
Other major cities include:
Boston
Chicago
Los Angeles
New York
Portland
San Francisco Bay Area
Seattle Area
I hope they add Canada soon!