Occupational licensing law research project (OLLRP)
Welcome to the first installment of our data project. This database was sourced and compiled by Dr. Morris Kleiner, Dr. Jason Hicks, Corissa Marson, Ethan Ellis, Evan Cunningham, Carol Wood, Dr. Wenchen Wang, and Dr. Nicholas Carollo, with generous financial support from the many sponsors listed below. This is the first installment of a longitudinal, historical project set out by the original authors which will now be updated and managed by researchers at the KRRC.
Sponsorship for this
project
include the following institutions:
Smith Richardson Foundation
Russell Sage Foundation
Charles Koch Foundation
Federal Reserve Bank of Minneapolis
Washington Center for Equitable Growth
Hoover Institution, Standford University
Humphrey School of Public Affairs, University of Minnesota
National Bureau of Economic Research
W.E. Upjohn Institute for Employment Research
The Hamilton Project, Brookings Institution
Minnesota Population Center (MPC), University of Minnesota
The Institute for Humane Studies at George Mason University
Ewing Marion Kauffman Foundation
The Knee Regulatory Research Center
This project is a success with many thanks and data support from Nicholas Carollo, senior
economist in the Labor Markets section of the Division of Research and Statistics
at the Federal Reserve Board of Governors. Carollo's paper "Historical Data on
Professional and Occupational Credentialing Requirements in the United States"
can be found
here, as well as his
GitHub page (2025), where you can find raw data and Stata code for
almost 300 occupations or license categories throughout all 50 states and DC,
covering most policies enacted from 1870 to 2019 for these occupations.
You will find below “universally licensed” and “partially licensed” occupations.
The universally licensed data variables are a subset of the variables you will
find in the data dictionary.
The following occupations are now available:
Partially Licensed:
- Cosmetologists
- Dispensing Opticians
- Licensed Practical Nurse
- Massage Therapist
- Professional Counselor
- Respiratory Therapist
The partially licensed data includes all variables from the data dictionary and
covers all pathways and requirements within the scope of this project.
- Optometrist
- Physician Assistant
- Physician
- Registered Nurse
The universally licensed data variables are a subset of the variables you will
find in the data dictionary. The data assumes required education is fixed at
its lowest level, and records other requirements given that assumption.
Other additions we look forward to adding in the future to the OLLRP database include:
- Code for a data walk-through for an occupation
- A forthcoming methodology paper
Note for use: Be sure to download and read both universal and partially licensed
occupations' data dictionary and read me files below (rows 1 & 2).
June 2025: Version 1 Database**
| Profession | Read.Me File | Licensed Type | Data Download File |
|---|---|---|---|
| PARTIALLY LICENSED | Download by occupation below | Partially licensed | Partial.Data.Dictionary |
| UNIVERSALLY LICENSED | Universal.Read.Me | Universally licensed | Universal.Data.Dictionary |
| Optometrist | Refer to Row 2* | Universally Licensed | Optometrist.Data |
| Physician Assistant | Row 2* | Universally Licensed | PA.Data |
| Physician | Row 2* | Universally Licensed | Physician.Data |
| Registered Nurse | Row 2* | Universally Licensed | RN.Data |
| Cosmetologist | Cosmetology.ReadMe | Partially Licensed | Cosmetologist.Data |
| Dispensing Optician | Dispensing.ReadMe | Partially Licensed | DispensingOpt.Data |
| Licensed Practical Nurse | LPN.ReadMe | Partially Licensed | LPN.Data |
| Massage Therapist | Massage.ReadMe | Partially Licensed | Massage.Data |
| Professional Counselor | Counselor.ReadMe | Partially Licensed | Counselor.Data |
| Respiratory Therapist | Respiratory.ReadMe | Partially Licensed | Respiratory.Data |
| Barber | Barber.ReadMe | Partially Licensed | Barber.Data |
| Shampooer | Shampoo.ReadMe | Partially Licensed | Shampoo.Data |
| Esthetician | Esthet.ReadMe | Partially Licensed | Esthet.Data |
| Embalmer | Emablm.ReadMe | Partially Licensed | Embalm.Data |
| Funeral Director | FuneralDir.ReadMe | Partially Licensed | FuneralDir.Data |
| Mortgage Broker | MortgBroker.ReadMe | Universally Licensed | MortgBroker.Data |
| Mortgage Loan Originator | MLO.ReadMe | Universally Licensed | MLO.Data |
*All universally licensed occupations' read me file can be found in the "Universal.Read.Me" download. Partially licensed
occupations have a read.me file for each occupation individually.
**Database may be adjusted for error or miscalculation in future versions. Any new versions of database uploads will be posted on a regular basis, while older versions will be available for download in the archived data at the bottom of this page.
Other Archived Data Versions:
- Version 1 minor revisions made to remove misleading variables and comments, and add clarifying notation, on Oct. 7, 2025. Any changes made are tracked in the Universal.Read.Me document. Reach out to kneecenter@mail.wvu.edu for first version database files, if necessary.
- Version 2 (updated 4/22/26) adds 7 new occupations to the database - barbers, shampooers, estheticians, embalmers, funeral directors, mortgage brokers, and mortgage loan originators.
Database Citation for Use: Kleiner, M., Hicks, J., Marson, C.,
Wood, C., Ellis, E., Cunningham, E., & Wang, W. (2025). "Occupational Licensing
Law Research Project." Knee Regulatory Research Center at West Virginia University.
Additional Citations: Carollo, N. (2020). "Historical data on professional and occupational credentialing requirements in the united states." Available at SSRN 3687130.
Additional Citations: Carollo, N. (2020). "Historical data on professional and occupational credentialing requirements in the united states." Available at SSRN 3687130.