Great Flood of 1993

https://en.wikipedia.org/wiki/Great_Flood_of_1993

The Great Flood of 1993 (or Great Mississippi and Missouri Rivers Flood of 1993) was a flood that occurred in the Midwestern United States, along the Mississippi and Missouri rivers and their tributaries, from April to October 1993. The flood was among the most costly and devastating to ever occur in the United States, with $15 billion in damages (approx. $26 billion in 2018 dollars). The hydrographic basin affected over around 745 miles (1,199 km) in length and 435 miles (700 km) in width, totaling about 320,000 square miles (830,000 km²).^[2] Within this zone, the flooded area totaled around 30,000 square miles (78,000 km²)^[3] and was the worst such U.S. disaster since the Great Mississippi Flood of 1927, as measured by duration, area inundated, persons displaced, crop and property damage, and number of record river levels. In some categories, the 1993 flood even surpassed the 1927 flood, at the time the largest flood ever recorded on the Mississippi.

https://en.wikipedia.org/wiki/Mississippi_River_floods#Flood_of_1788

Worst flooding in USA history, looking at all rivers--1927

Worst flooding for the lower Mississippi River.

1. 1927

2. 1973

3. 1937

4. 2011

Worst flooding for the Upper Mississippi River using actual discharge/levels

1. 1844

2. 1993

So although recent rains have been excessive and the most in over 2 decades for the Midwest and rains  HAVE increased from climate change and an atmosphere that can hold 6% more moisture, we have not exceeded records in the past.........other than at isolated locations, which is not unusual for extreme weather events.

I found a flood that was  worse than 1993 on the Upper Mississippi:

https://en.wikipedia.org/wiki/Mississippi_River_floods#Flood_of_1788

Great Flood of 1844

Main article: Great Flood of 1844

The largest flood ever recorded on the Missouri River and Upper Mississippi River in terms of discharge.  The adjusted economic impact was not as great as subsequent floods because of the small population in the region at the time.This flood was particularly devastating since the region had few if any levees at the time.  Among the hardest hit were the Wyandot who lost 100 people in the diseases that occurred after the flood.  The flood also is the highest recorded for the Mississippi River at St. Louis.  After the flood, Congress in 1849 passed the Swamp Act providing land grants to build stronger levees

Here a good link with information regarding flooding along the entire Mississippi  River. 

Mississippi River floods

https://en.wikipedia.org/wiki/Mississippi_River_floods