How much money are visitors allowed to bring in to and out the U.S. ?

I’m travelling with my family to the US this week. I have hospital appointments everyday for a week to get medical treatment as I’m visually impaired. Then, I’m going to Canada to obtain my Permanent Residency Card (PRC). So, I’m thinking to bring with me $30,000 – 40K U$D. Take into consideration that we are 5 travelers, 2 adults & 3 kids.

How much am I allowed to bring into the U.S.? & How much am I allowed to take with me when I’m travelling to Canada?

Do I need to declare the money? if so, would I be entitled to any taxes by the IRS?

P.S. I would appreciate it if you know about the regulations in both the U.S. & Canada.

Many Thanks!