I have the old list of US Zip Codes which is missing some of the zip codes.
How can I get the Updated list of Zip Codes in CSV format?
This question on GIS Stackexchange provides a good overview of why this is not as simple a request as you might think. Zip codes are created, maintained and updated frequently by the USPS (US Postal Service), not the census bureau. Their databases are not open or free.
However, if your previous dataset is from the 2010 Census, you probably don't actually want zip code data. Your dataset is probably the Census ZCTAs (Zip Code Tabulation Areas). In that case, be aware that:
ZIP Codes that cover primarily nonresidential or post office box addresses may not have a corresponding ZCTA because the delineation process uses primarily residential addresses, resulting in a bias towards ZIP Codes used for city-style mail delivery. (Source)
ZCTA data can be downloaded in shapefile format here. The shapefile download will include a DBF file, which you can open in Excel and save as a CSV. Here's what it looks like:
The first field, ZCTA5CE10, is the 2010 Census 5-digit ZIP Code Tabulation Area code (the most commonly used zip code in the ZCTA). The last two fields, INTPTLAT10 and INTPTLON10, are the 2010 Census latitude and longitude of an interior point (a point inside the zip code area).
The ZCTA shapefile for 2018 is actually from the 2010 census. 2019 TIGER files will be available in September, but the ZCTAs will presumably still be from the 2010 census. The next census will be in 2020, so keep an eye on the census bureau website for 2020 census data availability.
Here's what the TIGER/Line® Shapefiles 2018 Technical Documentation says about ZCTAs:
3.23 ZIP Code Tabulation Areas (5-digit)
ZIP Code tabulation area geography and attributes are available in the following shapefile:
5-Digit ZIP Code Tabulation Area (ZCTA5) National Shapefile (2010 Census)
ZIP Code tabulation areas (ZCTAs) are approximate area representations of U.S. Postal Service (USPS) 5-digit ZIP Code service areas that the Census Bureau creates using census blocks to present statistical data from censuses and surveys. The Census Bureau defines ZCTAs by allocating each block that contains addresses to a single ZIP Code tabulation area, usually to the ZCTA that reflects the most frequently occurring ZIP Code for the addresses within that block. Blocks that do not contain addresses but that are completely surrounded by a single ZIP Code tabulation area (enclaves) are assigned to the surrounding ZCTA; those surrounded by multiple ZCTAs will be added to a single ZCTA based on the longest shared border. The Census Bureau identifies 5-digit ZIP Code tabulation areas using a 5-character numeric code that represents the most frequently occurring USPS ZIP Code within that ZCTA. This code may contain leading zeros.
Data users should not use ZCTAs to identify the official USPS ZIP Code for mail delivery. The USPS makes periodic changes to ZIP Codes to support more efficient mail delivery. ZIP Codes that cover primarily nonresidential or post office box addresses may not have a corresponding ZCTA because the delineation process uses primarily residential addresses, resulting in a bias towards ZIP Codes used for city-style mail delivery. ZIP Code Tabulation Area Codes—The Census Bureau identifies 5-digit ZCTAs using a 5-digit code.
For more information, visit: https://www.census.gov/geo/reference/zctas.html.
As of 8/19/2019, that final link takes you to a generic page about geography on the census website.