Based on 33 food products prices in 78 Russian regions from 2003 to 2018 we estimate regional price threshold which leads to price convergence. We applied econometric tests for the unit root null hy‑ pothesis versus a nonlinear alternative, and the null of linearity versus a nonlinear alternative. About a 40% of time series corresponds to the three‑regime TAR‑model and weak form of the law of one price.