Mixed Data for States Column

Ok, so your original question is more

"I have state names for some rows and state abbreviations for other rows, in the same column.  I want to replace the state names with the correct abbreviations".

If so, you will need to get yourself a table with state names and abbreviations (a master table).  This could be from a spreadsheet or from a webpage - there will be lots around. Import that table.

You then need to do a merge with the existing table and the new 'States' table. This will be a left join on the 'ship to state' column and the statename column in the 'States' table.  You can then return the state abbreviation in a column. 

Some of them wil be null because the existing column has abbreviations already, or spelling errors or different variations of the name won't bring a match back.  You can tidy up the data at this stage to make matches more likely.

At that point you can add a column that says 'if returned column is null then original column else returned column'

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So, quite a lot there for people who are new to Power Query but all very possible.  I think the powerbi documentation has a similar example (from memory).  I'll check and post the link.