diff --git a/.github/workflows/unittests.yml b/.github/workflows/unittests.yml
index 7e9113f..47493b3 100644
--- a/.github/workflows/unittests.yml
+++ b/.github/workflows/unittests.yml
@@ -23,6 +23,8 @@
    unittests:
      name: micromamba (${{ matrix.os }}, ${{ matrix.environment-file }})
      runs-on: ${{ matrix.os }}
+     env:
+       RUN_TESTS: pytest -v nhgisxwalk --cov nhgisxwalk --doctest-modules --cov-config .coveragerc --cov-report xml
      timeout-minutes: 10
      strategy:
        matrix:
@@ -46,12 +48,12 @@
 
        - name: run tests - bash
          shell: bash -l {0}
-         run: pytest -v nhgisxwalk --cov=nhgisxwalk --doctest-modules --cov-config=.coveragerc --cov-report=xml
+         run: ${{ env.RUN_TESTS }}
          if: matrix.os != 'windows-latest'
        
        - name: run tests - powershell
          shell: powershell
-         run: pytest -v nhgisxwalk --cov=nhgisxwalk --doctest-modules --cov-config=.coveragerc --cov-report=xml
+         run: ${{ env.RUN_TESTS }}
          if: matrix.os == 'windows-latest'
      
        - name: codecov
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 40e3f4f..497273c 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -1,6 +1,6 @@
 repos: 
 -   repo: https://github.com/psf/black
-    rev: 20.8b1
+    rev: 21.12b0
     hooks: 
     - id: black
       language_version: python3.9
diff --git a/README.md b/README.md
index 323b800..9d11dae 100644
--- a/README.md
+++ b/README.md
@@ -46,7 +46,7 @@ This pacakge allows for the generation of temporal crosswalks of census geograph
 
 ## Installation
 
-Currently `nhgisxwalk` officially supports Python [3.7](https://docs.python.org/3.7/), [3.8](https://docs.python.org/3.8/), and [3.9](https://docs.python.org/3.9/). Please make sure that you are operating in a Python >= 3.7 environment. Install the most current development version of `nhgisxwalk` by running:
+Currently `nhgisxwalk` officially supports Python [3.8](https://docs.python.org/3.8/), [3.9](https://docs.python.org/3.9/), and [3.10](https://docs.python.org/3.10/). Please make sure that you are operating in a Python >= 3.8 environment. Install the most current development version of `nhgisxwalk` by running:
 
 ```
 $ pip install git+https://github.com/ipums/nhgisxwalk
diff --git a/ci/37.yaml b/ci/37.yaml
deleted file mode 100644
index 829ea83..0000000
--- a/ci/37.yaml
+++ /dev/null
@@ -1,18 +0,0 @@
-# This file is part of the Minnesota Population Center's NHGISXWALK.
-# For copyright and licensing information, see the NOTICE and LICENSE files
-# in this project's top-level directory, and also on-line at:
-#   https://github.com/ipums/nhgisxwalk
-
-name: test
-channels:
-  - conda-forge
-dependencies:
-  - python=3.7
-  # required
-  - numpy>=1.3
-  - pandas>=1.0
-  - watermark
-  # testing
-  - pytest
-  - pytest-cov
-  - codecov
diff --git a/setup.py b/setup.py
index 2861fca..c4834fb 100644
--- a/setup.py
+++ b/setup.py
@@ -80,7 +80,6 @@ def setup_package():
             "Topic :: Scientific/Engineering :: GIS",
             "License :: OSI Approved :: Mozilla Public License 2.0 (MPL 2.0)",
             "Programming Language :: Python",
-            "Programming Language :: Python :: 3.7",
             "Programming Language :: Python :: 3.8",
             "Programming Language :: Python :: 3.9",
             "Programming Language :: Python :: 3.10",
@@ -90,7 +89,7 @@ def setup_package():
         py_modules=[package],
         install_requires=reqs,
         zip_safe=False,
-        python_requires=">=3.7",
+        python_requires=">=3.8",
     )
 
 
diff --git a/testing_data_subsets/nhgis_blk1990_blk2010_gj.zip b/testing_data_subsets/nhgis_blk1990_blk2010_gj.zip
index d785aae..9568012 100644
Binary files a/testing_data_subsets/nhgis_blk1990_blk2010_gj.zip and b/testing_data_subsets/nhgis_blk1990_blk2010_gj.zip differ