436 - especially if you get the GPS - (or make your own via instructions found on the forums) and take the time to program the rectangles.
Hint:
https://www.maptechnica.com/search?type=city
You can use this tool to define bounding boxes for cities, counties, states, etc.
Imagine your scanner changing to the right frequencies as you drive - no diddling around.
I'll give you an example:
Here is the rectangles already compiled for all of WSP's districts.
Dist 1
Pierce - 47.403675 -122.852918 46.728406 -121.374115
Thurston - 47.19422 -123.203101 46.762038 -122.203106
Dist 2
King - 47.780576 -122.541661 47.08435 -121.065945
Dist 3
Asotin - 46.462245 -117.47999 45.995357 -116.916071
Benton - 46.727763 -119.876725 45.836198 -118.94106
Columbia - 46.624777 -118.24264 45.99895 -117.603296
Franklin - 46.739105 -119.457535 46.192667 -118.198228
Garfield - 46.703168 -117.863347 45.997801 -117.228009
Walla Walla - 46.606812 -119.041498 45.999855 -117.991481
Yakima - 47.08875 -121.52307 46.040169 -119.86554
Dist 4
Adams - 47.261718 -119.369507 46.73539 -117.959335
Ferry - 49.000092 -118.869983 47.830363 -118.104447
Lincoln - 47.957906 -118.979777 47.260011 -117.819405
Pend Oreille - 49.001201 -117.629611 48.045394 -117.032107
Spokane - 48.047779 -117.823629 47.259272 -117.039763
Stevens - 49.000738 -118.402407 47.792295 -117.429967
Whitman - 47.260659 -118.249389 46.416779 -117.039405
Dist 5
Clark - 46.059632 -122.795963 45.543541 -122.244515
Cowlitz - 46.388045 -123.218313 45.850536 -122.239481
Lewis - 46.794427 -123.372706 46.383458 -121.353179
Klickitat - 46.045104 -121.612731 45.606098 -119.865829
Skamania - 46.388629 -122.25021 45.548653 -121.51438
Dist 6
Chelan - 48.550836 -121.180802 47.260871 -119.859708
Douglas - 48.151187 -120.318084 47.220133 -118.950592
Grant - 47.962183 -120.042866 46.625464 -118.972823
Kittitas - 47.597939 -121.465979 46.736151 -119.925605
Okanogan - 49.000569 -120.88564 47.940857 -118.836409
Dist 7
Island - 48.417855 -122.863078 47.828098 -122.328463
San Juan - 48.831218 -123.267877 48.284558 -122.703316
Skagit - 48.657003 -122.764404 48.295945 -120.686097
Snohomish - 48.29899 -122.458596 47.775349 -120.907399
Whatcom - 49.002432 -123.322238 48.625687 -120.655857
Dist 8
Clallam - 48.499784 -124.848974 47.866673 -122.896971
Grays Harbor - 47.533898 -124.429553 46.790916 -123.158364
Jefferson - 48.370361 -124.717153 47.517715 -122.595401
Kitsap - 47.972953 -123.038404 47.403091 -122.427023
Mason - 47.607508 -123.50608 47.082259 -122.8005
Pacific - 46.794241 -124.175131 46.234949 -123.357387
Wahkiakum - 46.385617 -123.728316 46.144532 -123.213054