Mile markers on non-interstates

[lordsutch]

Here is the TxDOT page regarding milepost reference points:

http://onlinemanuals.txdot.gov/txdotmanuals/trm/reference_markers_coordinates.htm

Clear as mud to me.

It's not that complex.  Basically reference markers are set based on miles south and east of a hypothetical origin point 10 miles west and 10 miles north of the most extreme west and northernmost points in Texas (it works out to be somewhere NNW of Albuquerque); the first marker is at the northernmost or westernmost point of the route based on that grid.  Then each subsequent marker is 2 miles east or south of the previous marker.  This is why exit numbers on SH 130 increase as you go south.

Interstates don't do this; instead they're numbered traditionally starting at zero per MUTCD rules (south/west for 2dis, or following the spur and loop rules).

[mapman1071]

US1 through the Keys. Any toll freeway in Florida.

US1 Mile Markers In The Keys also correspond to Mail/Street Addresses of residents and businesses for example 2750 Highway 1 or 2750 Overseas Highway would be located between MM27 and MM28