Comparison of Deficit as a percentage of GDP
In FY 2017 the US federal deficit was 3.4 percent of GDP. This year, FY 2018, the federal government in its latest budget has estimated that the deficit will be 4.2 percent of GDP.
Canada recorded a Government Budget deficit equal to 0.90 percent of the country's Gross Domestic Product in 2017. Government Budget in Canada averaged -1.80 percent of GDP from 1949 until 2017, reaching an all time high of 5.10 percent of GDP in 1950 and a record low of -8.30 percent of GDP in 1985.
Comparison of debt as a percentage of GDP:
Canada recorded a government debt equivalent to 89.60 percent of the country's Gross Domestic Product in 2017. Government Debt to GDP in Canada averaged 78.07 percent from 1980 until 2017, reaching an all time high of 100.60 percent in 1996 and a record low of 45.10 percent in 1980.
The United States recorded a government debt equivalent to 105.40 percent of the country's Gross Domestic Product in 2017. Government Debt to GDP in the United States averaged 61.70 percent from 1940 until 2017, reaching an all time high of 118.90 percent in 1946 and a record low of 31.70 percent in 1981.
There is a point at which deficits and debt are no longer tenable. I don't know what that point is, but it appears that the US is closer to it.